An overdose of Amitriptyline can lead to the development of an anticholinergic toxidrome. This toxidrome is characterized by various symptoms, which can be remembered using the phrase ‘mad as a hatter, hot as hell, red as a beat, dry as a bone, and blind as a bat’. Some of these symptoms include a dry mouth and an elevated body temperature.

Further Reading:

Tricyclic antidepressant (TCA) overdose is a common occurrence in emergency departments, with drugs like amitriptyline and dosulepin being particularly dangerous. TCAs work by inhibiting the reuptake of norepinephrine and serotonin in the central nervous system. In cases of toxicity, TCAs block various receptors, including alpha-adrenergic, histaminic, muscarinic, and serotonin receptors. This can lead to symptoms such as hypotension, altered mental state, signs of anticholinergic toxicity, and serotonin receptor effects.

TCAs primarily cause cardiac toxicity by blocking sodium and potassium channels. This can result in a slowing of the action potential, prolongation of the QRS complex, and bradycardia. However, the blockade of muscarinic receptors also leads to tachycardia in TCA overdose. QT prolongation and Torsades de Pointes can occur due to potassium channel blockade. TCAs can also have a toxic effect on the myocardium, causing decreased cardiac contractility and hypotension.

Early symptoms of TCA overdose are related to their anticholinergic properties and may include dry mouth, pyrexia, dilated pupils, agitation, sinus tachycardia, blurred vision, flushed skin, tremor, and confusion. Severe poisoning can lead to arrhythmias, seizures, metabolic acidosis, and coma. ECG changes commonly seen in TCA overdose include sinus tachycardia, widening of the QRS complex, prolongation of the QT interval, and an R/S ratio >0.7 in lead aVR.

Management of TCA overdose involves ensuring a patent airway, administering activated charcoal if ingestion occurred within 1 hour and the airway is intact, and considering gastric lavage for life-threatening cases within 1 hour of ingestion. Serial ECGs and blood gas analysis are important for monitoring. Intravenous fluids and correction of hypoxia are the first-line therapies. IV sodium bicarbonate is used to treat haemodynamic instability caused by TCA overdose, and benzodiazepines are the treatment of choice for seizure control. Other treatments that may be considered include glucagon, magnesium sulfate, and intravenous lipid emulsion.

There are certain things to avoid in TCA overdose, such as anti-arrhythmics like quinidine and flecainide, as they can prolonged depolarization.

The Arthus reaction is a response that occurs when antigen/antibody complexes are formed in the skin after an antigen is injected. Although rare, these reactions can happen after receiving vaccines that contain tetanus toxoid or diphtheria toxoid. They are classified as a type III hypersensitivity reaction.

Arthus reactions are characterized by pain, swelling, induration, hemorrhage, and sometimes necrosis. Typically, these symptoms appear 4-12 hours after vaccination.

Type III hypersensitivity reactions occur when insoluble antigen-antibody complexes accumulate in different tissues and are not effectively cleared by the body’s innate immune cells. This leads to an inflammatory response in the affected tissues.

Some other examples of type III hypersensitivity reactions include immune complex glomerulonephritis, rheumatoid arthritis, systemic lupus erythematosus, serum sickness, and extrinsic allergic alveolitis.

Warfarin has been found to elevate the likelihood of bleeding events when taken in conjunction with NSAIDs like ibuprofen. Consequently, it is advisable to refrain from co-prescribing warfarin with ibuprofen. For more information on this topic, please refer to the BNF section on warfarin interactions.

The use of low-dose aspirin during pregnancy is considered safe and can be used to manage recurrent miscarriage, clotting disorders, and pre-eclampsia. On the other hand, high-dose aspirin carries several risks, especially if used in the third trimester. These risks include delayed onset of labor, premature closure of the fetal ductus arteriosus, and fetal kernicterus (a condition that affects the brain due to high levels of bilirubin). Additionally, there is a slight increase in the risk of first-trimester abortion if high-dose aspirin is used early in pregnancy.

Below is a list outlining commonly encountered drugs that have adverse effects during pregnancy:

Drug: ACE inhibitors (e.g. ramipril)
Adverse effects: If given in the second and third trimester, ACE inhibitors can cause hypoperfusion, renal failure, and the oligohydramnios sequence.

Drug: Aminoglycosides (e.g. gentamicin)
Adverse effects: Aminoglycosides can cause ototoxicity (damage to the ear) and deafness.

Drug: Aspirin
Adverse effects: High doses of aspirin can cause first-trimester abortions, delayed onset of labor, premature closure of the fetal ductus arteriosus, and fetal kernicterus. However, low doses (e.g. 75 mg) have no significant associated risk.

During the third trimester of pregnancy, the use of selective serotonin reuptake inhibitors (SSRIs) has been associated with a discontinuation syndrome and persistent pulmonary hypertension of the newborn. It is important to be aware of the adverse effects of various drugs during pregnancy. For example, ACE inhibitors like ramipril, if given in the second and third trimester, can cause hypoperfusion, renal failure, and the oligohydramnios sequence. Aminoglycosides such as gentamicin can lead to ototoxicity and deafness. High doses of aspirin can result in first-trimester abortions, delayed onset labor, premature closure of the fetal ductus arteriosus, and fetal kernicterus. However, low doses (e.g., 75 mg) do not pose significant risks. Late administration of benzodiazepines like diazepam during pregnancy can cause respiratory depression and a neonatal withdrawal syndrome. Calcium-channel blockers, if given in the first trimester, may cause phalangeal abnormalities, while their use in the second and third trimester can lead to fetal growth retardation. Carbamazepine has been associated with hemorrhagic disease of the newborn and neural tube defects. Chloramphenicol can cause grey baby syndrome. Corticosteroids, if given in the first trimester, may cause orofacial clefts. Danazol, if administered in the first trimester, can result in masculinization of the female fetuses genitals. Pregnant women should avoid handling crushed or broken tablets of finasteride as it can be absorbed through the skin and affect male sex organ development. Haloperidol, if given in the first trimester, may cause limb malformations, while its use in the third trimester increases the risk of extrapyramidal symptoms in the neonate. Heparin can lead to maternal bleeding and thrombocytopenia. Isoniazid can cause maternal liver damage and neuropathy and seizures in the neonate. Isotretinoin carries a high risk of teratogenicity, including multiple congenital malformations, spontaneous abortion, and intellectual disability. The use of lithium in the first trimester increases the risk of fetal cardiac malformations, while its use in the second and third trimesters can result in hypotonia, lethargy, feeding problems, hypothyroidism, goiter, and nephrogenic diabetes insipidus.

Potentially, there can be a serious condition called hypokalaemia, which is characterized by low levels of potassium in the body. This condition should be taken seriously, especially in cases of severe asthma, as it can be made worse by certain medications like theophyllines (such as aminophylline and Uniphyllin Continus), corticosteroids, and low oxygen levels. Additionally, the use of thiazide and loop diuretics can also worsen hypokalaemia. Therefore, it is important to regularly monitor the levels of potassium in the blood of individuals with severe asthma.

It is worth noting that spironolactone, a type of diuretic, is known as a potassium-sparing medication. This means that it does not typically contribute to hypokalaemia.

Opioid poisoning is a common occurrence in the Emergency Department. It can occur as a result of recreational drug use, such as heroin, or from prescribed opioids like morphine sulfate tablets or dihydrocodeine.

The symptoms of opioid overdose include a decreased level of consciousness or even coma, reduced respiratory rate, apnea, pinpoint pupils, low blood pressure, cyanosis, convulsions, and non-cardiogenic pulmonary edema (in cases of intravenous heroin usage). The most common cause of death from opioid overdose is respiratory depression, which typically happens within an hour of the overdose. Vomiting is also common, and there is a risk of aspiration.

Naloxone is the specific antidote for opioid overdose. It can reverse respiratory depression and coma if given in sufficient dosage. The initial intravenous dose is 400 micrograms, followed by 800 micrograms for up to two doses at one-minute intervals if there is no response to the preceding dose. If there is still no response, the dose may be increased to 2 mg for one dose (seriously poisoned patients may require a 4 mg dose). If the intravenous route is not feasible, naloxone can be given by intramuscular injection.

Since naloxone has a shorter duration of action than most opioids, close monitoring and repeated injections are necessary. The dosage should be adjusted based on the respiratory rate and depth of coma. Generally, the dose is repeated every 2-3 minutes, up to a maximum of 10 mg. In cases where repeated doses are needed, naloxone can be administered through a continuous infusion, with the infusion rate initially set at 60% of the initial resuscitative intravenous dose per hour.

In opioid addicts, the administration of naloxone may trigger a withdrawal syndrome, characterized by abdominal cramps, nausea, and diarrhea. However, these symptoms typically subside within 2 hours.

Digoxin-specific antibody fragments, known as Digibind or Digifab, are utilized for the treatment of digoxin toxicity. These antibody fragments should be readily available in all hospital pharmacies across the UK and accessible within a maximum of one hour.

Further Reading:

Digoxin is a medication used for rate control in atrial fibrillation and for improving symptoms in heart failure. It works by decreasing conduction through the atrioventricular node and increasing the force of cardiac muscle contraction. However, digoxin toxicity can occur, and plasma concentration alone does not determine if a patient has developed toxicity. Symptoms of digoxin toxicity include feeling generally unwell, lethargy, nausea and vomiting, anorexia, confusion, yellow-green vision, arrhythmias, and gynaecomastia.

ECG changes seen in digoxin toxicity include downsloping ST depression with a characteristic Salvador Dali sagging appearance, flattened, inverted, or biphasic T waves, shortened QT interval, mild PR interval prolongation, and prominent U waves. There are several precipitating factors for digoxin toxicity, including hypokalaemia, increasing age, renal failure, myocardial ischaemia, electrolyte imbalances, hypoalbuminaemia, hypothermia, hypothyroidism, and certain medications such as amiodarone, quinidine, verapamil, and diltiazem.

Management of digoxin toxicity involves the use of digoxin specific antibody fragments, also known as Digibind or digifab. Arrhythmias should be treated, and electrolyte disturbances should be corrected with close monitoring of potassium levels. It is important to note that digoxin toxicity can be precipitated by hypokalaemia, and toxicity can then lead to hyperkalaemia.

Carboxyhaemoglobin (COHb) blood levels are utilized for the identification of carbon monoxide poisoning. COHb is the substance produced when carbon monoxide attaches to haemoglobin. It is important to note that carbaminohemoglobin (also known as carbaminohaemoglobin, carboxyhemoglobin, and carbohemoglobin) is the compound formed when carbon dioxide binds to hemoglobin, and should not be mistaken for COHb.

Further Reading:

Carbon monoxide (CO) is a dangerous gas that is produced by the combustion of hydrocarbon fuels and can be found in certain chemicals. It is colorless and odorless, making it difficult to detect. In England and Wales, there are approximately 60 deaths each year due to accidental CO poisoning.

When inhaled, carbon monoxide binds to haemoglobin in the blood, forming carboxyhaemoglobin (COHb). It has a higher affinity for haemoglobin than oxygen, causing a left-shift in the oxygen dissociation curve and resulting in tissue hypoxia. This means that even though there may be a normal level of oxygen in the blood, it is less readily released to the tissues.

The clinical features of carbon monoxide toxicity can vary depending on the severity of the poisoning. Mild or chronic poisoning may present with symptoms such as headache, nausea, vomiting, vertigo, confusion, and weakness. More severe poisoning can lead to intoxication, personality changes, breathlessness, pink skin and mucosae, hyperpyrexia, arrhythmias, seizures, blurred vision or blindness, deafness, extrapyramidal features, coma, or even death.

To help diagnose domestic carbon monoxide poisoning, there are four key questions that can be asked using the COMA acronym. These questions include asking about co-habitees and co-occupants in the house, whether symptoms improve outside of the house, the maintenance of boilers and cooking appliances, and the presence of a functioning CO alarm.

Typical carboxyhaemoglobin levels can vary depending on whether the individual is a smoker or non-smoker. Non-smokers typically have levels below 3%, while smokers may have levels below 10%. Symptomatic individuals usually have levels between 10-30%, and severe toxicity is indicated by levels above 30%.

When managing carbon monoxide poisoning, the first step is to administer 100% oxygen. Hyperbaric oxygen therapy may be considered for individuals with a COHb concentration of over 20% and additional risk factors such as loss of consciousness, neurological signs, myocardial ischemia or arrhythmia, or pregnancy. Other management strategies may include fluid resuscitation, sodium bicarbonate for metabolic acidosis, and mannitol for cerebral edema.

Hypomagnesaemia frequently occurs alongside hypokalaemia. It is important to note that potassium levels may not improve with supplementation until the magnesium deficiency is addressed.

Further Reading:

Vasoactive drugs can be classified into three categories: inotropes, vasopressors, and unclassified. Inotropes are drugs that alter the force of muscular contraction, particularly in the heart. They primarily stimulate adrenergic receptors and increase myocardial contractility. Commonly used inotropes include adrenaline, dobutamine, dopamine, isoprenaline, and ephedrine.

Vasopressors, on the other hand, increase systemic vascular resistance (SVR) by stimulating alpha-1 receptors, causing vasoconstriction. This leads to an increase in blood pressure. Commonly used vasopressors include norepinephrine, metaraminol, phenylephrine, and vasopressin.

Electrolytes, such as potassium, are essential for proper bodily function. Solutions containing potassium are often given to patients to prevent or treat hypokalemia (low potassium levels). However, administering too much potassium can lead to hyperkalemia (high potassium levels), which can cause dangerous arrhythmias. It is important to monitor potassium levels and administer it at a controlled rate to avoid complications.

Hyperkalemia can be caused by various factors, including excessive potassium intake, decreased renal excretion, endocrine disorders, certain medications, metabolic acidosis, tissue destruction, and massive blood transfusion. It can present with cardiovascular, respiratory, gastrointestinal, and neuromuscular symptoms. ECG changes, such as tall tented T-waves, prolonged PR interval, flat P-waves, widened QRS complex, and sine wave, are also characteristic of hyperkalemia.

In summary, vasoactive drugs can be categorized as inotropes, vasopressors, or unclassified. Inotropes increase myocardial contractility, while vasopressors increase systemic vascular resistance. Electrolytes, particularly potassium, are important for bodily function, but administering too much can lead to hyperkalemia. Monitoring potassium levels and ECG changes is crucial in managing hyperkalemia.

St. John’s wort can reduce the effectiveness of warfarin, an anticoagulant medication. Therefore, it is important for patients who are taking warfarin to be aware that they should avoid using St. John’s wort as a supplement. For more information on this interaction, you can refer to the BNF section on warfarin interactions.

Cytochrome p450 enzyme inhibitors have the ability to enhance the effects of warfarin, leading to an increase in the International Normalized Ratio (INR). To remember the commonly encountered cytochrome p450 enzyme inhibitors, the mnemonic O DEVICES can be utilized. Each letter in the mnemonic represents a specific inhibitor: O for Omeprazole, D for Disulfiram, E for Erythromycin (as well as other macrolide antibiotics), V for Valproate (specifically sodium valproate), I for Isoniazid, C for Ciprofloxacin, E for Ethanol (when consumed acutely), and S for Sulphonamides.

Activated charcoal should be administered in cases of salicylate overdose if the patient arrives at the medical facility within one hour of ingestion and the amount ingested is greater than 125 mg per kilogram of body weight.

Further Reading:

Salicylate poisoning, particularly from aspirin overdose, is a common cause of poisoning in the UK. One important concept to understand is that salicylate overdose leads to a combination of respiratory alkalosis and metabolic acidosis. Initially, the overdose stimulates the respiratory center, leading to hyperventilation and respiratory alkalosis. However, as the effects of salicylate on lactic acid production, breakdown into acidic metabolites, and acute renal injury occur, it can result in high anion gap metabolic acidosis.

The clinical features of salicylate poisoning include hyperventilation, tinnitus, lethargy, sweating, pyrexia (fever), nausea/vomiting, hyperglycemia and hypoglycemia, seizures, and coma.

When investigating salicylate poisoning, it is important to measure salicylate levels in the blood. The sample should be taken at least 2 hours after ingestion for symptomatic patients or 4 hours for asymptomatic patients. The measurement should be repeated every 2-3 hours until the levels start to decrease. Other investigations include arterial blood gas analysis, electrolyte levels (U&Es), complete blood count (FBC), coagulation studies (raised INR/PTR), urinary pH, and blood glucose levels.

To manage salicylate poisoning, an ABC approach should be followed to ensure a patent airway and adequate ventilation. Activated charcoal can be administered if the patient presents within 1 hour of ingestion. Oral or intravenous fluids should be given to optimize intravascular volume. Hypokalemia and hypoglycemia should be corrected. Urinary alkalinization with intravenous sodium bicarbonate can enhance the elimination of aspirin in the urine. In severe cases, hemodialysis may be necessary.

Urinary alkalinization involves targeting a urinary pH of 7.5-8.5 and checking it hourly. It is important to monitor for hypokalemia as alkalinization can cause potassium to shift from plasma into cells. Potassium levels should be checked every 1-2 hours.

In cases where the salicylate concentration is high (above 500 mg/L in adults or 350 mg/L in children), sodium bicarbonate can be administered intravenously. Hemodialysis is the treatment of choice for severe poisoning and may be indicated in cases of high salicylate levels, resistant metabolic acidosis, acute kidney injury, pulmonary edema, seizures and coma..

Theophylline is a medication used to treat severe asthma. It is a bronchodilator that comes in modified-release forms, which can maintain therapeutic levels in the blood for 12 hours. Theophylline works by inhibiting phosphodiesterase and blocking the breakdown of cyclic AMP. It also competes with adenosine on A1 and A2 receptors.

Achieving the right dose of theophylline can be challenging because there is a narrow range between therapeutic and toxic levels. The half-life of theophylline can be influenced by various factors, further complicating dosage adjustments. It is recommended to aim for serum levels of 10-20 mg/l six to eight hours after the last dose.

Unlike many other medications, the specific brand of theophylline can significantly impact its effects. Therefore, it is important to prescribe theophylline by both its brand name and generic name.

Several factors can increase the half-life of theophylline, including heart failure, cirrhosis, viral infections, and certain drugs. Conversely, smoking, heavy drinking, and certain medications can decrease the half-life of theophylline.

There are several drugs that can either increase or decrease the plasma concentration of theophylline. Calcium channel blockers, cimetidine, fluconazole, macrolides, methotrexate, and quinolones can increase the concentration. On the other hand, carbamazepine, phenobarbitol, phenytoin, rifampicin, and St. John’s wort can decrease the concentration.

The clinical symptoms of theophylline toxicity are more closely associated with acute overdose rather than chronic overexposure. Common symptoms include headache, dizziness, nausea, vomiting, abdominal pain, rapid heartbeat, dysrhythmias, seizures, mild metabolic acidosis, low potassium, low magnesium, low phosphates, abnormal calcium levels, and high blood sugar.

Seizures are more prevalent in acute overdose cases, while chronic overdose typically presents with minimal gastrointestinal symptoms. Cardiac dysrhythmias are more common in chronic overdose situations compared to acute overdose.

During the later stages of pregnancy, the use of diazepam has been linked to respiratory depression in newborns and a withdrawal syndrome. There are several drugs that can have adverse effects during pregnancy, and the list below outlines the most commonly encountered ones.

ACE inhibitors, such as ramipril, can cause hypoperfusion, renal failure, and the oligohydramnios sequence if given in the second and third trimesters. Aminoglycosides, like gentamicin, can lead to ototoxicity and deafness. High doses of aspirin can result in first-trimester abortions, delayed onset labor, premature closure of the fetal ductus arteriosus, and fetal kernicterus. However, low doses (e.g., 75 mg) do not pose significant risks.

Benzodiazepines, including diazepam, can cause respiratory depression and a neonatal withdrawal syndrome when administered late in pregnancy. Calcium-channel blockers can cause phalangeal abnormalities if given in the first trimester and fetal growth retardation if given in the second and third trimesters. Carbamazepine can lead to hemorrhagic disease of the newborn and neural tube defects.

Chloramphenicol is associated with grey baby syndrome. Corticosteroids, if given in the first trimester, may cause orofacial clefts. Danazol, when administered in the first trimester, can cause masculinization of the female fetuses genitals. Pregnant women should avoid handling crushed or broken tablets of finasteride as it can affect male sex organ development.

Haloperidol, if given in the first trimester, may cause limb malformations. In the third trimester, there is an increased risk of extrapyramidal symptoms in the neonate. Heparin can lead to maternal bleeding and thrombocytopenia. Isoniazid can cause maternal liver damage and neuropathy and seizures in the neonate. Isotretinoin carries a high risk of teratogenicity, including multiple congenital malformations, spontaneous abortion, and intellectual disability.

Lithium, if given in the first trimester, poses a risk of fetal cardiac malformations. In the second and third trimesters, it can result in hypotonia, lethargy, feeding problems, hypothyroidism, goiter, and nephrogenic diabetes insipidus in the neonate.

There are various specific remedies available for different types of poisons and overdoses. The following list provides an outline of some of these antidotes:

Poison: Benzodiazepines
Antidote: Flumazenil

Poison: Beta-blockers
Antidotes: Atropine, Glucagon, Insulin

Poison: Carbon monoxide
Antidote: Oxygen

Poison: Cyanide
Antidotes: Hydroxocobalamin, Sodium nitrite, Sodium thiosulphate

Poison: Ethylene glycol
Antidotes: Ethanol, Fomepizole

Poison: Heparin
Antidote: Protamine sulphate

Poison: Iron salts
Antidote: Desferrioxamine

Poison: Isoniazid
Antidote: Pyridoxine

Poison: Methanol
Antidotes: Ethanol, Fomepizole

Poison: Opioids
Antidote: Naloxone

Poison: Organophosphates
Antidotes: Atropine, Pralidoxime

Poison: Paracetamol
Antidotes: Acetylcysteine, Methionine

Poison: Sulphonylureas
Antidotes: Glucose, Octreotide

Poison: Thallium
Antidote: Prussian blue

Poison: Warfarin
Antidote: Vitamin K, Fresh frozen plasma (FFP)

By utilizing these specific antidotes, medical professionals can effectively counteract the harmful effects of various poisons and overdoses.

When furosemide and gentamicin are prescribed together, there is a higher chance of experiencing ototoxicity and deafness. It is recommended to avoid co-prescribing these medications. For more information, you can refer to the BNF section on furosemide interactions.

Flumazenil is a specific antagonist for benzodiazepines that can be beneficial in certain situations. It acts quickly, taking less than 1 minute to take effect, but its effects are short-lived and only last for less than 1 hour. The recommended dosage is 200 μg every 1-2 minutes, with a maximum dose of 3mg per hour.

It is important to avoid using Flumazenil if the patient is dependent on benzodiazepines or is taking tricyclic antidepressants. This is because it can trigger a withdrawal syndrome in these individuals, potentially leading to seizures or cardiac arrest.

The therapeutic range for lithium typically falls between 0.4-0.8 mmol/l, although this range may differ depending on the laboratory. In general, the lower end of the range is the desired level for maintenance therapy and treatment in older individuals. Toxic effects are typically observed when levels exceed 1.5 mmol/l.

Warfarin has been found to heighten the likelihood of bleeding events when consumed alongside specific juices, such as cranberry juice and grapefruit juice. As a result, individuals who are taking warfarin should be cautioned against consuming these beverages. For more information on this topic, please refer to the BNF section on warfarin interactions and the interaction between warfarin and cranberry juice.

The use of antibiotics can impact the effectiveness of warfarin and other coumarin anticoagulants. This can lead to changes in the International Normalized Ratio (INR) and, in severe cases, increase the risk of bleeding. Some antibiotics, such as chloramphenicol, ciprofloxacin, co-trimoxazole, doxycycline, erythromycin, macrolides (e.g., clarithromycin), metronidazole, ofloxacin, and sulphonamide, are known to enhance the anticoagulant effect of warfarin. However, cefalexin is considered relatively safe and is the most suitable option in this situation.

Calcium-channel blocker overdose is a serious matter and should always be treated as potentially life-threatening. The two most dangerous types of calcium channel blockers in overdose are verapamil and diltiazem. These medications work by binding to the alpha-1 subunit of L-type calcium channels, which prevents the entry of calcium into cells. These channels play a crucial role in the functioning of cardiac myocytes, vascular smooth muscle cells, and islet beta-cells.

The toxic effects of calcium-channel blockers can be summarized as follows:

Cardiac effects:
– Excessive negative inotropy: causing myocardial depression
– Negative chronotropy: leading to sinus bradycardia
– Negative dromotropy: resulting in atrioventricular node blockade

Vascular smooth muscle tone effects:
– Decreased afterload: causing systemic hypotension
– Coronary vasodilation: leading to widened blood vessels in the heart

Metabolic effects:
– Hypoinsulinaemia: insulin release depends on calcium influx through L-type calcium channels in islet beta-cells
– Calcium channel blocker-induced insulin resistance: causing reduced responsiveness to insulin.

It is important to be aware of these effects and take appropriate action in cases of calcium-channel blocker overdose.

Corneal microdeposits are found in almost all individuals (over 90%) who have been taking amiodarone for more than six months, particularly at doses higher than 400 mg/day. These deposits generally do not cause any symptoms, although approximately 10% of patients may experience a perception of a ‘bluish halo’ around objects they see.

Amiodarone can also have other effects on the eye, but these are much less common, occurring in only 1-2% of patients. These effects include optic neuropathy, nonarteritic anterior ischemic optic neuropathy (N-AION), optic disc swelling, and visual field defects.

Activated charcoal is a commonly used substance for decontamination in cases of poisoning. Its main function is to adsorb the molecules of the ingested toxin onto its surface.

Activated charcoal is a chemically inert form of carbon. It is a fine black powder that has no odor or taste. It is produced by subjecting carbonaceous matter to high heat, a process known as pyrolysis, and then treating it with a zinc chloride solution to increase its concentration. This process creates a network of pores within the charcoal, giving it a large absorptive area of approximately 3,000 m2/g. This allows it to effectively inhibit the absorption of toxins by up to 50%.

The usual dose of activated charcoal is 50 grams for adults and 1 gram per kilogram of body weight for children. It can be administered orally or through a nasogastric tube. It is important to administer it within one hour of ingestion, and it may be repeated after one hour if necessary.

However, there are certain situations where activated charcoal should not be used. These include cases where the patient is unconscious or in a coma, as there is a risk of aspiration. It should also be avoided if seizures are imminent, as there is a risk of aspiration. Additionally, if there is reduced gastrointestinal motility, activated charcoal should not be used to prevent the risk of obstruction.

Activated charcoal is effective in treating overdose with certain drugs and toxins, such as aspirin, paracetamol, barbiturates, tricyclic antidepressants, digoxin, amphetamines, morphine, cocaine, and phenothiazines. However, it is ineffective in cases of overdose with iron, lithium, boric acid, cyanide, ethanol, ethylene glycol, methanol, malathion, DDT, carbamate, hydrocarbon, strong acids, or alkalis.

There are potential adverse effects associated with the use of activated charcoal. These include nausea and vomiting, diarrhea, constipation, bezoar formation (a mass of undigested material that can cause blockages), bowel obstruction, pulmonary aspiration (inhalation of charcoal into the lungs), and impaired absorption of oral medications or antidotes.

First-generation antipsychotics, also known as conventional or typical antipsychotics, are powerful blockers of the dopamine D2 receptor. However, each drug in this category has different effects on other receptors, such as serotonin type 2 (5-HT2), alpha1, histaminic, and muscarinic receptors.

These first-generation antipsychotics are known to have a high incidence of extrapyramidal side effects, which include rigidity, bradykinesia, dystonias, tremor, akathisia, tardive dyskinesia, and neuroleptic malignant syndrome (NMS). NMS is a rare and life-threatening reaction to neuroleptic medications, characterized by fever, muscle stiffness, changes in mental state, and dysfunction of the autonomic nervous system. NMS typically occurs shortly after starting or increasing the dose of neuroleptic treatment.

On the other hand, second-generation antipsychotics, also referred to as novel or atypical antipsychotics, are dopamine D2 antagonists, except for aripiprazole. These medications are associated with lower rates of extrapyramidal side effects and NMS compared to the first-generation antipsychotics. However, they have higher rates of metabolic side effects and weight gain.

It is important to note that serotonin syndrome shares similar features with NMS but can be distinguished by the causative agent, most commonly the serotonin-specific reuptake inhibitors.

In cases of anaphylaxis, it is important to administer non-sedating antihistamines after adrenaline administration and initial resuscitation. Previous guidelines recommended the use of chlorpheniramine and hydrocortisone as third line treatments, but the 2021 guidelines have removed this recommendation. Corticosteroids are no longer advised. Instead, it is now recommended to use non-sedating antihistamines such as cetirizine, loratadine, and fexofenadine, as alternatives to the sedating antihistamine chlorpheniramine. The top priority treatments for anaphylaxis are adrenaline, oxygen, and fluids. The Resuscitation Council advises that administration of non-sedating antihistamines should occur after the initial resuscitation.

Further Reading:

Anaphylaxis is a severe and life-threatening hypersensitivity reaction that can have sudden onset and progression. It is characterized by skin or mucosal changes and can lead to life-threatening airway, breathing, or circulatory problems. Anaphylaxis can be allergic or non-allergic in nature.

In allergic anaphylaxis, there is an immediate hypersensitivity reaction where an antigen stimulates the production of IgE antibodies. These antibodies bind to mast cells and basophils. Upon re-exposure to the antigen, the IgE-covered cells release histamine and other inflammatory mediators, causing smooth muscle contraction and vasodilation.

Non-allergic anaphylaxis occurs when mast cells degrade due to a non-immune mediator. The clinical outcome is the same as in allergic anaphylaxis.

The management of anaphylaxis is the same regardless of the cause. Adrenaline is the most important drug and should be administered as soon as possible. The recommended doses for adrenaline vary based on age. Other treatments include high flow oxygen and an IV fluid challenge. Corticosteroids and chlorpheniramine are no longer recommended, while non-sedating antihistamines may be considered as third-line treatment after initial stabilization of airway, breathing, and circulation.

Common causes of anaphylaxis include food (such as nuts, which is the most common cause in children), drugs, and venom (such as wasp stings). Sometimes it can be challenging to determine if a patient had a true episode of anaphylaxis. In such cases, serum tryptase levels may be measured, as they remain elevated for up to 12 hours following an acute episode of anaphylaxis.

The Resuscitation Council (UK) provides guidelines for the management of anaphylaxis, including a visual algorithm that outlines the recommended steps for treatment.
https://www.resus.org.uk/sites/default/files/2021-05/Emergency%20Treatment%20of%20Anaphylaxis%20May%202021_0.pdf

Amiodarone has a chemical structure that is similar to thyroxine and has the ability to bind to the nuclear thyroid receptor. This medication has the potential to cause both hypothyroidism and hyperthyroidism, although hypothyroidism is more commonly observed, affecting around 5-10% of patients.

There are several side effects associated with the use of amiodarone. These include the formation of microdeposits in the cornea, increased sensitivity to sunlight resulting in photosensitivity, feelings of nausea, disturbances in sleep patterns, and the development of either hyperthyroidism or hypothyroidism. In addition, there have been reported cases of acute hepatitis and jaundice, peripheral neuropathy, lung fibrosis, and QT prolongation.

It is important to be aware of these potential side effects when considering the use of amiodarone as a treatment option. Regular monitoring and close medical supervision are necessary to detect and manage any adverse reactions that may occur.

There is an increased risk of neural tube defects in women with epilepsy who take carbamazepine during pregnancy, ranging from 2 to 10 times higher. Additionally, there is a risk of haemorrhagic disease of the newborn associated with this medication. It is crucial to have discussions about epilepsy treatments with women of childbearing age during the planning stages so that they can start early supplementation of folic acid.

Below is a list outlining the most commonly encountered drugs that have adverse effects during pregnancy:

ACE inhibitors (e.g. ramipril): If given in the second and third trimester, these medications can cause hypoperfusion, renal failure, and the oligohydramnios sequence.

Aminoglycosides (e.g. gentamicin): These drugs can lead to ototoxicity and deafness in the fetus.

Aspirin: High doses of aspirin can cause first-trimester abortions, delayed onset labor, premature closure of the fetal ductus arteriosus, and fetal kernicterus. However, low doses (e.g. 75 mg) do not pose significant risks.

Benzodiazepines (e.g. diazepam): When given late in pregnancy, these medications can result in respiratory depression and a neonatal withdrawal syndrome.

Calcium-channel blockers: If given in the first trimester, these drugs can cause phalangeal abnormalities. If given in the second and third trimesters, they can lead to fetal growth retardation.

Carbamazepine: This medication is associated with haemorrhagic disease of the newborn and neural tube defects.

Chloramphenicol: Use of this drug can cause grey baby syndrome in newborns.

Corticosteroids: If given in the first trimester, corticosteroids may cause orofacial clefts in the fetus.

Danazol: When administered in the first trimester, danazol can cause masculinization of the female fetuses genitals.

Finasteride: Pregnant women should avoid handling finasteride tablets. Crushed or broken tablets can be absorbed through the skin and affect male sex organ development in the fetus.

Haloperidol: If given in the first trimester, haloperidol may cause limb malformations. In the third trimester, there is an increased risk of extrapyramidal symptoms in the neonate.

Heparin: Use of heparin during pregnancy is associated with an acceptable bleeding rate and a low rate of thrombotic recurrence in the mother.

Activated charcoal is a useful treatment for many drug poisonings, but it is not effective against certain types of poisonings. To remember these exceptions, you can use the mnemonic PHAILS. This stands for Pesticides (specifically organophosphates), Hydrocarbons, Acids (strong), alkalis (strong), alcohols (such as ethanol, methanol, and ethylene glycol), Iron, Lithium, and Solvents.

Further Reading:

Poisoning in the emergency department is often caused by accidental or intentional overdose of prescribed drugs. Supportive treatment is the primary approach for managing most poisonings. This includes ensuring a clear airway, proper ventilation, maintaining normal fluid levels, temperature, and blood sugar levels, correcting any abnormal blood chemistry, controlling seizures, and assessing and treating any injuries.

In addition to supportive treatment, clinicians may need to consider strategies for decontamination, elimination, and administration of antidotes. Decontamination involves removing poisons from the skin or gastrointestinal tract. This can be done through rinsing the skin or using methods such as activated charcoal, gastric lavage, induced emesis, or whole bowel irrigation. However, induced emesis is no longer commonly used, while gastric lavage and whole bowel irrigation are rarely used.

Elimination methods include urinary alkalinization, hemodialysis, and hemoperfusion. These techniques help remove toxins from the body.

Activated charcoal is a commonly used method for decontamination. It works by binding toxins in the gastrointestinal tract, preventing their absorption. It is most effective if given within one hour of ingestion. However, it is contraindicated in patients with an insecure airway due to the risk of aspiration. Activated charcoal can be used for many drugs, but it is ineffective for certain poisonings, including pesticides (organophosphates), hydrocarbons, strong acids and alkalis, alcohols (ethanol, methanol, ethylene glycol), iron, lithium, and solvents.

Antidotes are specific treatments for poisoning caused by certain drugs or toxins. For example, cyanide poisoning can be treated with dicobalt edetate, hydroxocobalamin, or sodium nitrite and sodium thiosulphate. Benzodiazepine poisoning can be treated with flumazanil, while opiate poisoning can be treated with naloxone. Other examples include protamine for heparin poisoning, vitamin K or fresh frozen plasma for warfarin poisoning, fomepizole or ethanol for methanol poisoning, and methylene blue for methemoglobinemia caused by benzocaine or nitrates.

There are many other antidotes available for different types of poisoning, and resources such as TOXBASE and the National Poisons Information Service (NPIS) can provide valuable advice on managing poisonings.

The key components of first aid for snake bites in the UK involve immobilizing the patient and the affected limb, as well as administering paracetamol for pain relief. When it comes to venomous snake bites, it is important to immobilize the limb using a splint or sling, but not to use a tourniquet or pressure bandage for adder bites. In certain areas, such as NSW, Australia, where venomous snakes can cause rapidly progressing and life-threatening paralysis, pressure bandage immobilization is recommended. However, this is not the case in the UK. Anti-venom is not always necessary for adder bites, and its administration should be based on a thorough assessment of the patient’s condition and the presence of appropriate indications. Paracetamol is the preferred choice for pain relief in UK snake bites, as aspirin and ibuprofen can worsen bleeding tendencies that may result from adder bites. Similarly, heparin should be avoided for the same reason.

Further Reading:

Snake bites in the UK are primarily caused by the adder, which is the only venomous snake species native to the country. While most adder bites result in minor symptoms such as pain, swelling, and inflammation, there have been cases of life-threatening illness and fatalities. Additionally, there are instances where venomous snakes that are kept legally or illegally also cause bites in the UK.

Adder bites typically occur from early spring to late autumn, with the hand being the most common site of the bite. Symptoms can be local or systemic, with local symptoms including sharp pain, tingling or numbness, and swelling that spreads proximally. Systemic symptoms may include spreading pain, tenderness, inflammation, regional lymph node enlargement, and bruising. In severe cases, anaphylaxis can occur, leading to symptoms such as nausea, vomiting, abdominal pain, diarrhea, and shock.

It is important for clinicians to be aware of the potential complications and complications associated with adder bites. These can include acute renal failure, pulmonary and cerebral edema, acute gastric dilatation, paralytic ileus, acute pancreatitis, and coma and seizures. Anaphylaxis symptoms can appear within minutes or be delayed for hours, and hypotension is a critical sign to monitor.

Initial investigations for adder bites include blood tests, ECG, and vital sign monitoring. Further investigations such as chest X-ray may be necessary based on clinical signs. Blood tests may reveal abnormalities such as leukocytosis, raised hematocrit, anemia, thrombocytopenia, and abnormal clotting profile. ECG changes may include tachyarrhythmias, bradyarrhythmias, atrial fibrillation, and ST segment changes.

First aid measures at the scene include immobilizing the patient and the bitten limb, avoiding aspirin and ibuprofen, and cleaning the wound site in the hospital. Tetanus prophylaxis should be considered. In cases of anaphylaxis, prompt administration of IM adrenaline is necessary. In the hospital, rapid assessment and appropriate resuscitation with intravenous fluids are required.

Antivenom may be indicated in cases of hypotension, systemic envenoming, ECG abnormalities, peripheral neutrophil leucocytosis, elevated serum creatine kinase or metabolic acidosis, and extensive or rapidly spreading local swelling. Zagreb antivenom is commonly used in the UK, with an initial dose of 8 mL.

There is a significant link between methotrexate and the development of pulmonary fibrosis. While there have been instances of pulmonary fibrosis occurring as a result of infliximab, this particular side effect is more commonly associated with methotrexate use.

Methotrexate can also cause other side effects such as nausea and vomiting, abdominal pain, gastrointestinal bleeding, dizziness, stomatitis, hepatotoxicity, neutropenia, and pneumonitis.

Prolongation of the QT interval can lead to a dangerous ventricular arrhythmia called torsades de pointes, which can result in sudden cardiac death. There are several commonly used medications that are known to cause QT prolongation.

Low levels of potassium (hypokalaemia) and magnesium (hypomagnesaemia) can increase the risk of QT prolongation. For example, diuretics can interact with QT-prolonging drugs by causing hypokalaemia.

The QT interval varies with heart rate, and formulas are used to correct the QT interval for heart rate. Once corrected, it is referred to as the QTc interval. The QTc interval is typically reported on the ECG printout. A normal QTc interval is less than 440 ms.

If the QTc interval is greater than 440 ms but less than 500 ms, it is considered borderline. Although there may be some variation in the literature, a QTc interval within these values is generally considered borderline prolonged. In such cases, it is important to consider reducing the dose of QT-prolonging drugs or switching to an alternative medication that does not prolong the QT interval.

A prolonged QTc interval exceeding 500 ms is clinically significant and is likely to increase the risk of arrhythmia. Any medications that prolong the QT interval should be reviewed immediately.

Here are some commonly encountered drugs that are known to prolong the QT interval:

Antimicrobials:
– Erythromycin
– Clarithromycin
– Moxifloxacin
– Fluconazole
– Ketoconazole

Antiarrhythmics:
– Dronedarone
– Sotalol
– Quinidine
– Amiodarone
– Flecainide

Antipsychotics:
– Risperidone
– Fluphenazine
– Haloperidol
– Pimozide
– Chlorpromazine
– Quetiapine
– Clozapine

Antidepressants:
– Citalopram/escitalopram
– Amitriptyline
– Clomipramine
– Dosulepin
– Doxepin
– Imipramine
– Lofepramine

Antiemetics:
– Domperidone
– Droperidol
– Ondansetron/Granisetron

Others:
– Methadone
– Protein kinase inhibitors (e.g. sunitinib)

If someone consumes at least 75 mg of paracetamol per kilogram of body weight within a 24-hour period, it is considered to be a significant ingestion. Ingesting more than 150 mg of paracetamol per kilogram of body weight within 24 hours poses a serious risk of harm.

Further Reading:

Paracetamol poisoning occurs when the liver is unable to metabolize paracetamol properly, leading to the production of a toxic metabolite called N-acetyl-p-benzoquinone imine (NAPQI). Normally, NAPQI is conjugated by glutathione into a non-toxic form. However, during an overdose, the liver’s conjugation systems become overwhelmed, resulting in increased production of NAPQI and depletion of glutathione stores. This leads to the formation of covalent bonds between NAPQI and cell proteins, causing cell death in the liver and kidneys.

Symptoms of paracetamol poisoning may not appear for the first 24 hours or may include abdominal symptoms such as nausea and vomiting. After 24 hours, hepatic necrosis may develop, leading to elevated liver enzymes, right upper quadrant pain, and jaundice. Other complications can include encephalopathy, oliguria, hypoglycemia, renal failure, and lactic acidosis.

The management of paracetamol overdose depends on the timing and amount of ingestion. Activated charcoal may be given if the patient presents within 1 hour of ingesting a significant amount of paracetamol. N-acetylcysteine (NAC) is used to increase hepatic glutathione production and is given to patients who meet specific criteria. Blood tests are taken to assess paracetamol levels, liver function, and other parameters. Referral to a medical or liver unit may be necessary, and psychiatric follow-up should be considered for deliberate overdoses.

In cases of staggered ingestion, all patients should be treated with NAC without delay. Blood tests are also taken, and if certain criteria are met, NAC can be discontinued. Adverse reactions to NAC are common and may include anaphylactoid reactions, rash, hypotension, and nausea. Treatment for adverse reactions involves medications such as chlorpheniramine and salbutamol, and the infusion may be stopped if necessary.

The prognosis for paracetamol poisoning can be poor, especially in cases of severe liver injury. Fulminant liver failure may occur, and liver transplant may be necessary. Poor prognostic indicators include low arterial pH, prolonged prothrombin time, high plasma creatinine, and hepatic encephalopathy.

Phenytoin is a potent anti-epileptic drug that is no longer recommended as the initial treatment for generalized or partial epilepsy due to its toxic effects. Users often experience common symptoms such as ataxia, nystagmus, diplopia, tremor, and dysarthria. Additionally, other side effects may include depression, decreased cognitive abilities, coarse facial features, acne, gum enlargement, polyneuropathy, and blood disorders.

First-generation antipsychotics, also known as conventional or typical antipsychotics, are potent blockers of dopamine D2 receptors. However, these drugs also have varying effects on other receptors such as serotonin type 2 (5-HT2), alpha1, histaminic, and muscarinic receptors.

One of the major drawbacks of first-generation antipsychotics is their high incidence of extrapyramidal side effects. These include rigidity, bradykinesia, dystonias, tremor, akathisia, and tardive dyskinesia. Additionally, there is a rare but life-threatening reaction called neuroleptic malignant syndrome (NMS) that can occur with these medications. NMS is characterized by fever, muscle rigidity, altered mental status, and autonomic dysfunction. It typically occurs shortly after starting or increasing the dose of a neuroleptic medication.

In contrast, second-generation antipsychotics, also known as novel or atypical antipsychotics, have a lower risk of extrapyramidal side effects and NMS compared to their first-generation counterparts. However, they are associated with higher rates of metabolic effects and weight gain.

It is important to differentiate serotonin syndrome from NMS as they share similar features. Serotonin syndrome is most commonly caused by serotonin-specific reuptake inhibitors.

Here are some commonly encountered examples of first- and second-generation antipsychotics:

First-generation:
– Chlopromazine
– Haloperidol
– Fluphenazine
– Trifluoperazine

Second-generation:
– Clozapine
– Olanzapine
– Quetiapine
– Risperidone
– Aripiprazole

Grey baby syndrome is a rare but serious side effect that can occur in neonates, especially premature babies, as a result of the build-up of the antibiotic chloramphenicol. This condition is characterized by several symptoms, including ashen grey skin color, poor feeding, vomiting, cyanosis, hypotension, hypothermia, hypotonia, cardiovascular collapse, abdominal distension, and respiratory difficulties.

During pregnancy, there are several drugs that can have adverse effects on the developing fetus. ACE inhibitors, such as ramipril, if given in the second and third trimesters, can lead to hypoperfusion, renal failure, and the oligohydramnios sequence. Aminoglycosides, like gentamicin, can cause ototoxicity and deafness. High doses of aspirin can result in first-trimester abortions, delayed onset labor, premature closure of the fetal ductus arteriosus, and fetal kernicterus. However, low doses of aspirin (e.g., 75 mg) do not pose significant risks.

Benzodiazepines, such as diazepam, when administered late in pregnancy, can cause respiratory depression and a neonatal withdrawal syndrome. Calcium-channel blockers, if given in the first trimester, may lead to phalangeal abnormalities, while their use in the second and third trimesters can result in fetal growth retardation. Carbamazepine can cause hemorrhagic disease of the newborn and neural tube defects.

Chloramphenicol, as mentioned earlier, can cause grey baby syndrome. Corticosteroids, if given in the first trimester, may cause orofacial clefts. Danazol, if administered in the first trimester, can cause masculinization of the female fetuses genitals. Pregnant women should avoid handling crushed or broken tablets of finasteride, as it can be absorbed through the skin and affect male sex organ development.

Haloperidol, if given in the first trimester, may cause limb malformations, while its use in the third trimester increases the risk of extrapyramidal symptoms in the neonate. Heparin can lead to maternal bleeding and thrombocytopenia. Isoniazid can cause maternal liver damage and neuropathy and seizures in the neonate. Isotretinoin carries a high risk of teratogenicity, including multiple congenital malformations, spontaneous abortion, and intellectual disability.

Loop diuretics, like furosemide, commonly result in several electrolyte imbalances. These imbalances include hyponatremia, which is a decrease in sodium levels in the blood. Another common imbalance is hypokalemia, which refers to low levels of potassium. Additionally, loop diuretics can cause hypocalcemia, a condition characterized by low levels of calcium in the blood. Another electrolyte affected by loop diuretics is magnesium, as they can lead to hypomagnesemia, which is a deficiency of magnesium. Lastly, loop diuretics can cause hypochloremic alkalosis, which is a condition characterized by low levels of chloride in the blood and an increase in blood pH.

Ipratropium bromide commonly leads to dry mouth as a side effect. Additionally, it may result in constipation, cough, sudden bronchospasm, headache, nausea, and palpitations. In patients with prostatic hyperplasia and bladder outflow obstruction, it can cause urinary retention. Furthermore, susceptible individuals may experience acute closed-angle glaucoma as a result of using this medication.

In the latest guideline published in 2021 by RCEM and NPIS regarding antidote availability for emergency departments, it is emphasized that immediate access to sodium bicarbonate is essential for treating TCA overdose. It is worth noting that previous versions of the guideline included glucagon as a recommended treatment for TCA overdose, but this reference has been omitted in the latest edition.

Further Reading:

Salicylate poisoning, particularly from aspirin overdose, is a common cause of poisoning in the UK. One important concept to understand is that salicylate overdose leads to a combination of respiratory alkalosis and metabolic acidosis. Initially, the overdose stimulates the respiratory center, leading to hyperventilation and respiratory alkalosis. However, as the effects of salicylate on lactic acid production, breakdown into acidic metabolites, and acute renal injury occur, it can result in high anion gap metabolic acidosis.

The clinical features of salicylate poisoning include hyperventilation, tinnitus, lethargy, sweating, pyrexia (fever), nausea/vomiting, hyperglycemia and hypoglycemia, seizures, and coma.

When investigating salicylate poisoning, it is important to measure salicylate levels in the blood. The sample should be taken at least 2 hours after ingestion for symptomatic patients or 4 hours for asymptomatic patients. The measurement should be repeated every 2-3 hours until the levels start to decrease. Other investigations include arterial blood gas analysis, electrolyte levels (U&Es), complete blood count (FBC), coagulation studies (raised INR/PTR), urinary pH, and blood glucose levels.

To manage salicylate poisoning, an ABC approach should be followed to ensure a patent airway and adequate ventilation. Activated charcoal can be administered if the patient presents within 1 hour of ingestion. Oral or intravenous fluids should be given to optimize intravascular volume. Hypokalemia and hypoglycemia should be corrected. Urinary alkalinization with intravenous sodium bicarbonate can enhance the elimination of aspirin in the urine. In severe cases, hemodialysis may be necessary.

Urinary alkalinization involves targeting a urinary pH of 7.5-8.5 and checking it hourly. It is important to monitor for hypokalemia as alkalinization can cause potassium to shift from plasma into cells. Potassium levels should be checked every 1-2 hours.

In cases where the salicylate concentration is high (above 500 mg/L in adults or 350 mg/L in children), sodium bicarbonate can be administered intravenously. Hemodialysis is the treatment of choice for severe poisoning and may be indicated in cases of high salicylate levels, resistant metabolic acidosis, acute kidney injury, pulmonary edema, seizures and coma.

An overdose of aspirin often leads to a combination of respiratory alkalosis and metabolic acidosis. Initially, the stimulation of the respiratory center causes hyperventilation and results in respiratory alkalosis. However, as the overdose progresses, the direct acidic effects of aspirin cause an increase in the anion gap and metabolic acidosis.

Here is a summary of common causes for different acid-base disorders:

Respiratory alkalosis can be caused by hyperventilation due to factors such as anxiety, pulmonary embolism, CNS disorders (such as stroke or encephalitis), altitude, pregnancy, and the early stages of aspirin overdose.

Respiratory acidosis can occur in individuals with chronic obstructive pulmonary disease (COPD), life-threatening asthma, pulmonary edema, sedative drug overdose (such as opioids or benzodiazepines), neuromuscular diseases, and obesity.

Metabolic alkalosis can be caused by vomiting, potassium depletion (often due to diuretic usage), Cushing’s syndrome, and Conn’s syndrome.

Metabolic acidosis with a raised anion gap can result from conditions such as lactic acidosis (caused by factors like hypoxemia, shock, sepsis, or tissue infarction), ketoacidosis (associated with diabetes, starvation, or excessive alcohol consumption), renal failure, and poisoning (including the late stages of aspirin overdose, methanol or ethylene glycol ingestion).

Metabolic acidosis with a normal anion gap can be seen in renal tubular acidosis, diarrhea, ammonium chloride ingestion, and adrenal insufficiency.

To ensure prompt response in case of an adverse reaction, it is important to have adrenaline, antihistamine, and steroid readily available when administering Zagreb antivenom.

Further Reading:

Snake bites in the UK are primarily caused by the adder, which is the only venomous snake species native to the country. While most adder bites result in minor symptoms such as pain, swelling, and inflammation, there have been cases of life-threatening illness and fatalities. Additionally, there are instances where venomous snakes that are kept legally or illegally also cause bites in the UK.

Adder bites typically occur from early spring to late autumn, with the hand being the most common site of the bite. Symptoms can be local or systemic, with local symptoms including sharp pain, tingling or numbness, and swelling that spreads proximally. Systemic symptoms may include spreading pain, tenderness, inflammation, regional lymph node enlargement, and bruising. In severe cases, anaphylaxis can occur, leading to symptoms such as nausea, vomiting, abdominal pain, diarrhea, and shock.

It is important for clinicians to be aware of the potential complications and complications associated with adder bites. These can include acute renal failure, pulmonary and cerebral edema, acute gastric dilatation, paralytic ileus, acute pancreatitis, and coma and seizures. Anaphylaxis symptoms can appear within minutes or be delayed for hours, and hypotension is a critical sign to monitor.

Initial investigations for adder bites include blood tests, ECG, and vital sign monitoring. Further investigations such as chest X-ray may be necessary based on clinical signs. Blood tests may reveal abnormalities such as leukocytosis, raised hematocrit, anemia, thrombocytopenia, and abnormal clotting profile. ECG changes may include tachyarrhythmias, bradyarrhythmias, atrial fibrillation, and ST segment changes.

First aid measures at the scene include immobilizing the patient and the bitten limb, avoiding aspirin and ibuprofen, and cleaning the wound site in the hospital. Tetanus prophylaxis should be considered. In cases of anaphylaxis, prompt administration of IM adrenaline is necessary. In the hospital, rapid assessment and appropriate resuscitation with intravenous fluids are required.

Antivenom may be indicated in cases of hypotension, systemic envenoming, ECG abnormalities, peripheral neutrophil leucocytosis, elevated serum creatine kinase or metabolic acidosis, and extensive or rapidly spreading local swelling. Zagreb antivenom is commonly used in the UK, with an initial dose of 8 mL.

There are various specific remedies available for different types of poisons and overdoses. The following list provides an outline of some of these antidotes:

Poison: Benzodiazepines
Antidote: Flumazenil

Poison: Beta-blockers
Antidotes: Atropine, Glucagon, Insulin

Poison: Carbon monoxide
Antidote: Oxygen

Poison: Cyanide
Antidotes: Hydroxocobalamin, Sodium nitrite, Sodium thiosulphate

Poison: Ethylene glycol
Antidotes: Ethanol, Fomepizole

Poison: Heparin
Antidote: Protamine sulphate

Poison: Iron salts
Antidote: Desferrioxamine

Poison: Isoniazid
Antidote: Pyridoxine

Poison: Methanol
Antidotes: Ethanol, Fomepizole

Poison: Opioids
Antidote: Naloxone

Poison: Organophosphates
Antidotes: Atropine, Pralidoxime

Poison: Paracetamol
Antidotes: Acetylcysteine, Methionine

Poison: Sulphonylureas
Antidotes: Glucose, Octreotide

Poison: Thallium
Antidote: Prussian blue

Poison: Warfarin
Antidote: Vitamin K, Fresh frozen plasma (FFP)

By utilizing these specific antidotes, medical professionals can effectively counteract the harmful effects of various poisons and overdoses.

Non-selective beta-blockers, like propranolol, can cause severe bronchospasm in individuals with asthma, particularly when taken in high doses. The current guidelines from the British Thoracic Society (BTS) recommend avoiding the use of beta-blockers in asthma patients. However, there is some evidence suggesting that the long-term use of cardioselective beta-blockers does not appear to trigger asthma attacks in individuals with mild or moderate asthma.

Beta-blockers play a crucial role in the treatment of patients who have a history of previous myocardial infarction or systolic dysfunction. In individuals with asthma and one of these diagnoses, it is unlikely that the potential benefits of beta-blockers outweigh the risks of worsening asthma symptoms.

There are various specific remedies available for different types of poisons and overdoses. The following list provides an outline of some of these antidotes:

Poison: Benzodiazepines
Antidote: Flumazenil

Poison: Beta-blockers
Antidotes: Atropine, Glucagon, Insulin

Poison: Carbon monoxide
Antidote: Oxygen

Poison: Cyanide
Antidotes: Hydroxocobalamin, Sodium nitrite, Sodium thiosulphate

Poison: Ethylene glycol
Antidotes: Ethanol, Fomepizole

Poison: Heparin
Antidote: Protamine sulphate

Poison: Iron salts
Antidote: Desferrioxamine

Poison: Isoniazid
Antidote: Pyridoxine

Poison: Methanol
Antidotes: Ethanol, Fomepizole

Poison: Opioids
Antidote: Naloxone

Poison: Organophosphates
Antidotes: Atropine, Pralidoxime

Poison: Paracetamol
Antidotes: Acetylcysteine, Methionine

Poison: Sulphonylureas
Antidotes: Glucose, Octreotide

Poison: Thallium
Antidote: Prussian blue

Poison: Warfarin
Antidote: Vitamin K, Fresh frozen plasma (FFP)

By utilizing these specific antidotes, medical professionals can effectively counteract the harmful effects of various poisons and overdoses.

Salicylate poisoning is a fairly common form of poisoning that can lead to organ damage and death if not treated promptly. The symptoms of salicylate poisoning include nausea, vomiting, ringing in the ears, hearing loss, excessive sweating, dehydration, rapid breathing, flushed skin, and high fever in children. In severe cases, convulsions, swelling of the brain, coma, kidney failure, fluid in the lungs, and unstable heart function can occur.

The treatment for salicylate poisoning involves stabilizing the patient’s airway, breathing, and circulation as needed, preventing further absorption of the poison, enhancing its elimination from the body, correcting any metabolic abnormalities, and providing supportive care. Unfortunately, there is no specific antidote available for salicylates. If a large amount of salicylate has been ingested within the past hour (more than 4.5 grams in adults or more than 2 grams in children), gastric lavage (stomach pumping) and administration of activated charcoal (50 grams) are recommended to reduce absorption and increase elimination.

Medical investigations for salicylate poisoning should include measuring the level of salicylate in the blood, analyzing arterial blood gases, performing an electrocardiogram (ECG), checking blood glucose levels, assessing kidney function and electrolyte levels, and evaluating blood clotting. ECG abnormalities that may be present include widening of the QRS complex, AV block, and ventricular arrhythmias.

The severity of salicylate poisoning is determined by the level of salicylate in the blood. Mild poisoning is defined as a salicylate level below 450 mg/L, moderate poisoning is between 450-700 mg/L, and severe poisoning is above 700 mg/L. In severe cases, aggressive intravenous fluid therapy is necessary to correct dehydration, and administration of 1.26% sodium bicarbonate can help eliminate the salicylate from the body. It is important to maintain a urine pH of greater than 7.5, ideally between 8.0-8.5. However, forced alkaline diuresis is no longer recommended. Life-threatening cases may require admission to the intensive care unit, intubation and ventilation, and possibly hemodialysis.

Intralipid is a lipid emulsion that is commonly used as a source of nutrition in parenteral nutrition. However, it has also been found to be effective in treating local anesthetic toxicity. When administered intravenously, Intralipid acts as a lipid sink, meaning it can bind to the local anesthetic agent and remove it from the affected tissues, thereby reversing the toxic effects.

In cases of cardiac arrest related to local anesthetic toxicity, Intralipid can be administered as a bolus followed by an infusion. The recommended dose is typically 1.5 mL/kg bolus over 1 minute, followed by an infusion of 0.25 mL/kg/minute for 10 minutes. This can be repeated if necessary.

It is important to note that while Intralipid has shown promising results in treating local anesthetic toxicity, it should not replace standard ALS protocols. Basic life support (BLS) measures, such as cardiopulmonary resuscitation (CPR), should still be initiated immediately, and advanced cardiac life support (ACLS) protocols should be followed.

Further Reading:

Local anaesthetics, such as lidocaine, bupivacaine, and prilocaine, are commonly used in the emergency department for topical or local infiltration to establish a field block. Lidocaine is often the first choice for field block prior to central line insertion. These anaesthetics work by blocking sodium channels, preventing the propagation of action potentials.

However, local anaesthetics can enter the systemic circulation and cause toxic side effects if administered in high doses. Clinicians must be aware of the signs and symptoms of local anaesthetic systemic toxicity (LAST) and know how to respond. Early signs of LAST include numbness around the mouth or tongue, metallic taste, dizziness, visual and auditory disturbances, disorientation, and drowsiness. If not addressed, LAST can progress to more severe symptoms such as seizures, coma, respiratory depression, and cardiovascular dysfunction.

The management of LAST is largely supportive. Immediate steps include stopping the administration of local anaesthetic, calling for help, providing 100% oxygen and securing the airway, establishing IV access, and controlling seizures with benzodiazepines or other medications. Cardiovascular status should be continuously assessed, and conventional therapies may be used to treat hypotension or arrhythmias. Intravenous lipid emulsion (intralipid) may also be considered as a treatment option.

If the patient goes into cardiac arrest, CPR should be initiated following ALS arrest algorithms, but lidocaine should not be used as an anti-arrhythmic therapy. Prolonged resuscitation may be necessary, and intravenous lipid emulsion should be administered. After the acute episode, the patient should be transferred to a clinical area with appropriate equipment and staff for further monitoring and care.

It is important to report cases of local anaesthetic toxicity to the appropriate authorities, such as the National Patient Safety Agency in the UK or the Irish Medicines Board in the Republic of Ireland. Additionally, regular clinical review should be conducted to exclude pancreatitis, as intravenous lipid emulsion can interfere with amylase or lipase assays.

Lipid emulsion is known to cause pancreatitis as a common side effect. According to the AAGBI guidelines, patients who are given lipid emulsion should be closely monitored with regular clinical evaluations. This includes conducting amylase or lipase tests daily for two days after receiving the emulsion.

Further Reading:

Local anaesthetics, such as lidocaine, bupivacaine, and prilocaine, are commonly used in the emergency department for topical or local infiltration to establish a field block. Lidocaine is often the first choice for field block prior to central line insertion. These anaesthetics work by blocking sodium channels, preventing the propagation of action potentials.

However, local anaesthetics can enter the systemic circulation and cause toxic side effects if administered in high doses. Clinicians must be aware of the signs and symptoms of local anaesthetic systemic toxicity (LAST) and know how to respond. Early signs of LAST include numbness around the mouth or tongue, metallic taste, dizziness, visual and auditory disturbances, disorientation, and drowsiness. If not addressed, LAST can progress to more severe symptoms such as seizures, coma, respiratory depression, and cardiovascular dysfunction.

The management of LAST is largely supportive. Immediate steps include stopping the administration of local anaesthetic, calling for help, providing 100% oxygen and securing the airway, establishing IV access, and controlling seizures with benzodiazepines or other medications. Cardiovascular status should be continuously assessed, and conventional therapies may be used to treat hypotension or arrhythmias. Intravenous lipid emulsion (intralipid) may also be considered as a treatment option.

If the patient goes into cardiac arrest, CPR should be initiated following ALS arrest algorithms, but lidocaine should not be used as an anti-arrhythmic therapy. Prolonged resuscitation may be necessary, and intravenous lipid emulsion should be administered. After the acute episode, the patient should be transferred to a clinical area with appropriate equipment and staff for further monitoring and care.

It is important to report cases of local anaesthetic toxicity to the appropriate authorities, such as the National Patient Safety Agency in the UK or the Irish Medicines Board in the Republic of Ireland. Additionally, regular clinical review should be conducted to exclude pancreatitis, as intravenous lipid emulsion can interfere with amylase or lipase assays.

Thiazide diuretics, like bendroflumethiazide and hydrochlorothiazide, have the potential to raise levels of uric acid in the blood, which can worsen gout symptoms in individuals who are susceptible to the condition.

Other medications, such as diuretics, beta-blockers, ACE inhibitors, and non-losartan ARBs, are also linked to an increased risk of gout.

On the other hand, calcium-channel blockers like amlodipine and verapamil, as well as losartan, have been found to lower uric acid levels and are associated with a reduced risk of gout.

The use of trimethoprim during the first trimester of pregnancy is linked to a higher risk of neural tube defects due to its interference with folate. If it is not possible to use an alternative antibiotic, it is recommended that pregnant women taking trimethoprim also take high-dose folic acid. However, the use of trimethoprim during the second and third trimesters of pregnancy is considered safe.

Here is a list outlining the commonly encountered drugs that have adverse effects during pregnancy:

ACE inhibitors (e.g. ramipril): If given in the second and third trimesters, they can cause hypoperfusion, renal failure, and the oligohydramnios sequence.

Aminoglycosides (e.g. gentamicin): They can cause ototoxicity and deafness.

Aspirin: High doses can lead to first-trimester abortions, delayed onset labor, premature closure of the fetal ductus arteriosus, and fetal kernicterus. However, low doses (e.g. 75 mg) do not pose significant risks.

Benzodiazepines (e.g. diazepam): When given late in pregnancy, they can cause respiratory depression and a neonatal withdrawal syndrome.

Calcium-channel blockers: If given in the first trimester, they can cause phalangeal abnormalities. If given in the second and third trimesters, they can lead to fetal growth retardation.

Carbamazepine: It can cause haemorrhagic disease of the newborn and neural tube defects.

Chloramphenicol: It can cause grey baby syndrome.

Corticosteroids: If given in the first trimester, they may cause orofacial clefts.

Danazol: If given in the first trimester, it can cause masculinization of the female fetuses genitals.

Finasteride: Pregnant women should avoid handling finasteride as crushed or broken tablets can be absorbed through the skin and affect male sex organ development.

Haloperidol: If given in the first trimester, it may cause limb malformations. If given in the third trimester, there is an increased risk of extrapyramidal symptoms in the neonate.

Heparin: It can cause maternal bleeding and thrombocytopenia.

Isoniazid: It can lead to maternal liver damage and neuropathy and seizures in the neonate.

The cardiotoxic effects of TCAs occur when they block sodium channels, leading to broadening of the QRS complex, and potassium channels, resulting in prolongation of the QT interval. The severity of adverse events is directly related to the degree of QRS broadening. If the QRS complex is greater than 100 ms, it is likely that seizures may occur. If the QRS complex exceeds 160 ms, ventricular arrhythmias may be predicted. In cases of TCA overdose, certain changes can be observed on an ECG. These include sinus tachycardia, which is very common, prolongation of the PR interval, broadening of the QRS complex, prolongation of the QT interval, and in severe cases, ventricular arrhythmias.