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.

An overdose of Amitriptyline, a tricyclic antidepressant, leads to a toxic effect known as anticholinergic toxidrome. This occurs when the muscarinic acetylcholine receptors are blocked, causing the characteristic signs and symptoms associated with this condition.

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.

Aminoglycosides have the ability to pass through the placenta and can lead to damage to the 8th cranial nerve in the fetus, resulting in permanent bilateral deafness.

ACE inhibitors, such as ramipril, can cause hypoperfusion, renal failure, and the oligohydramnios sequence if given in the 2nd and 3rd trimesters.

Aminoglycosides, like gentamicin, can cause ototoxicity and deafness in the fetus.

High doses of aspirin can lead to 1st 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, when administered late in pregnancy, can result in respiratory depression and a neonatal withdrawal syndrome.

Calcium-channel blockers, if given in the 1st trimester, can cause phalangeal abnormalities. If given in the 2nd and 3rd trimesters, they can lead to fetal growth retardation.

Carbamazepine can cause hemorrhagic disease of the newborn and neural tube defects.

Chloramphenicol is associated with grey baby syndrome.

Corticosteroids, if given in the 1st trimester, may cause orofacial clefts.

Danazol, if given in the 1st trimester, can cause masculinization of the female fetuses genitals.

Finasteride should not be handled by pregnant women as crushed or broken tablets can be absorbed through the skin and affect male sex organ development.

Haloperidol, if given in the 1st trimester, may cause limb malformations. If given in the 3rd 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 1st trimester, poses a risk of fetal cardiac malformations.

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 temperatures, a process known as pyrolysis, and then concentrating it with a zinc chloride solution. This creates a network of pores within the charcoal, giving it a large absorptive area of approximately 3,000 m2/g. This porous structure helps prevent the absorption of the harmful toxin by up to 50%.

The usual dosage 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 give the charcoal 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. If the patient is unconscious or in a coma, there is a risk of aspiration, so the charcoal should not be given. Similarly, if seizures are likely to occur, there is a risk of aspiration and the charcoal should be avoided. Additionally, if there is reduced gastrointestinal motility, there is a risk of obstruction, so activated charcoal should not be used in such cases.

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

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

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.

Digoxin is a medication used to treat atrial fibrillation and flutter as well as congestive cardiac failure. It belongs to a class of drugs called cardiac glycosides. Digoxin works by inhibiting the Na/K ATPase pump in the cardiac myocytes, which are the cells of the heart. This inhibition leads to an increase in the concentration of sodium inside the cells and indirectly increases the availability of calcium through the Na/Ca exchange mechanism. The rise in intracellular calcium levels results in a positive inotropic effect, meaning it strengthens the force of the heart’s contractions, and a negative chronotropic effect, meaning it slows down the heart rate.

However, it’s important to note that digoxin can cause toxicity, which is characterized by high levels of potassium in the blood, known as hyperkalemia. Normally, the Na/K ATPase pump helps maintain the balance of sodium and potassium by allowing sodium to leave the cells and potassium to enter. When digoxin blocks this pump, it disrupts this balance and leads to higher levels of potassium in the bloodstream.

Interestingly, the risk of developing digoxin toxicity is higher in individuals with low levels of potassium, known as hypokalemia. This is because digoxin binds to the ATPase pump at the same site as potassium. When potassium levels are low, digoxin can more easily bind to the ATPase pump and exert its inhibitory effects.

In summary, digoxin is a cardiac glycoside that is used to treat certain heart conditions. It works by inhibiting the Na/K ATPase pump, leading to increased intracellular calcium levels and resulting in a positive inotropic effect and negative chronotropic effect. However, digoxin can also cause toxicity, leading to high levels of potassium in the blood. The risk of toxicity is higher in individuals with low potassium levels.

The clinical manifestations of theophylline toxicity are more closely associated with acute poisoning rather than chronic overexposure. The primary clinical features of theophylline toxicity include headache, dizziness, nausea and vomiting, abdominal pain, tachycardia and dysrhythmias, seizures, mild metabolic acidosis, hypokalaemia, hypomagnesaemia, hypophosphataemia, hypo- or hypercalcaemia, and hyperglycaemia. Seizures are more prevalent in cases of acute overdose compared to chronic overexposure. In contrast, chronic theophylline overdose typically presents with minimal gastrointestinal symptoms. Cardiac dysrhythmias are more frequently observed in individuals who have experienced chronic overdose rather than acute overdose.

Salicylate poisoning initially leads to respiratory alkalosis, followed by metabolic acidosis. Salicylates, like aspirin, stimulate the respiratory center in the medulla, causing hyperventilation and respiratory alkalosis. This is usually the first acid-base imbalance observed in salicylate poisoning. As aspirin is metabolized, it disrupts oxidative phosphorylation in the mitochondria, leading to an increase in lactate levels due to anaerobic metabolism. The accumulation of lactic acid and acidic metabolites then causes metabolic acidosis.

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.

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

Early on in the overdose, arterial blood gas analysis typically reveals a respiratory alkalosis due to overstimulation of the respiratory center. As the overdose progresses, especially in moderate to severe cases, a metabolic acidosis with an increased anion gap may develop as a result of elevated levels of protons in the blood.

Electrocardiogram (ECG) abnormalities that may be observed include widening of the QRS complex, atrioventricular (AV) block, and ventricular arrhythmias.

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.

Haloperidol, when administered during the third trimester of pregnancy, can lead to extrapyramidal symptoms in the newborn. These symptoms may include agitation, poor feeding, excessive sleepiness, and difficulty breathing. The severity of these side effects can vary, with some infants requiring intensive care and extended hospital stays. It is important to closely monitor exposed neonates for signs of extrapyramidal syndrome or withdrawal. Haloperidol should only be used during pregnancy if the benefits clearly outweigh the risks to the fetus.

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

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

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

Aspirin: High doses of aspirin can lead to first-trimester abortions, delayed onset of 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 administered late in pregnancy, these drugs can cause respiratory depression and a neonatal withdrawal syndrome.

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

Carbamazepine: This drug can lead to hemorrhagic disease of the newborn and neural tube defects.

Chloramphenicol: Administration of chloramphenicol can cause gray baby syndrome in newborns.

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

Danazol: When administered during the first trimester, danazol 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 during the first trimester, haloperidol may cause limb malformations. If given during the third trimester, there is an increased risk of extrapyramidal symptoms in the neonate.

Digoxin is a medication used to manage heart failure and atrial fibrillation. It works by inhibiting the Na+/K+ ATPase in the myocardium, which slows down the ventricular response and has a positive effect on the heart’s contraction. Although less commonly used nowadays, digoxin still plays a role in certain cases.

One advantage of digoxin is its long half-life, allowing for once-daily maintenance doses. However, it is important to monitor the dosage to ensure it is correct and to watch out for factors that may lead to toxicity, such as renal dysfunction and hypokalemia. Once a steady state has been achieved, regular monitoring of plasma digoxin concentrations is not necessary unless there are concerns.

In atrial fibrillation, the effectiveness of digoxin treatment is best assessed by monitoring the ventricular rate. The target range for plasma digoxin concentration is 1.0-1.5 nmol/L, although higher levels of up to 2 nmol/L may be needed in some cases. It is important to note that the plasma concentration alone cannot reliably indicate toxicity, but levels above 2 nmol/L significantly increase the risk. To manage hypokalemia, which can increase the risk of digoxin toxicity, a potassium-sparing diuretic or potassium supplementation may be prescribed.

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.

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.

Atropine and pralidoxime are both considered antidotes for treating organophosphate poisoning. Organophosphates work by inhibiting acetylcholinesterase at nerve synapses. In addition to providing supportive care and administering antidotes, it is important to decontaminate patients as part of their treatment plan for organophosphate poisoning.

While both atropine and pralidoxime are recognized as antidotes, pralidoxime is not commonly used. Atropine works by competing with acetylcholine at the muscarinic receptors. On the other hand, pralidoxime helps reactivate acetylcholinesterase-organophosphate complexes that have not lost an alkyl side chain, known as non-aged complexes. However, pralidoxime is not effective against organophosphates that have already formed or rapidly form aged acetylcholinesterase complexes. The evidence regarding the effectiveness of pralidoxime is conflicting.

Further Reading:

Chemical incidents can occur as a result of leaks, spills, explosions, fires, terrorism, or the use of chemicals during wars. Industrial sites that use chemicals are required to conduct risk assessments and have accident plans in place for such incidents. Health services are responsible for decontamination, unless mass casualties are involved, and all acute health trusts must have major incident plans in place.

When responding to a chemical incident, hospitals prioritize containment of the incident and prevention of secondary contamination, triage with basic first aid, decontamination if not done at the scene, recognition and management of toxidromes (symptoms caused by exposure to specific toxins), appropriate supportive or antidotal treatment, transfer to definitive treatment, a safe end to the hospital response, and continuation of business after the event.

To obtain advice when dealing with chemical incidents, the two main bodies are Toxbase and the National Poisons Information Service. Signage on containers carrying chemicals and material safety data sheets (MSDS) accompanying chemicals also provide information on the chemical contents and their hazards.

Contamination in chemical incidents can occur in three phases: primary contamination from the initial incident, secondary contamination spread via contaminated people leaving the initial scene, and tertiary contamination spread to the environment, including becoming airborne and waterborne. The ideal personal protective equipment (PPE) for chemical incidents is an all-in-one chemical-resistant overall with integral head/visor and hands/feet worn with a mask, gloves, and boots.

Decontamination of contaminated individuals involves the removal and disposal of contaminated clothing, followed by either dry or wet decontamination. Dry decontamination is suitable for patients contaminated with non-caustic chemicals and involves blotting and rubbing exposed skin gently with dry absorbent material. Wet decontamination is suitable for patients contaminated with caustic chemicals and involves a warm water shower while cleaning the body with simple detergent.

After decontamination, the focus shifts to assessing the extent of any possible poisoning and managing it. The patient’s history should establish the chemical the patient was exposed to, the volume and concentration of the chemical, the route of exposure, any protective measures in place, and any treatment given. Most chemical poisonings require supportive care using standard resuscitation principles, while some chemicals have specific antidotes. Identifying toxidromes can be useful in guiding treatment, and specific antidotes may be administered accordingly.

Enzyme-inducing anticonvulsants have been found to enhance the metabolism of ethinyl estradiol and progestogens. This increased breakdown diminishes the effectiveness of the oral contraceptive pill (OCP) in preventing pregnancy. Some examples of enzyme-inducing anticonvulsants include carbamazepine, phenytoin, phenobarbitol, and topiramate.

On the other hand, non-enzyme-inducing anticonvulsants are unlikely to have an impact on contraception. Some examples of these anticonvulsants are sodium valproate, clonazepam, gabapentin, levetiracetam, and piracetam.

It is important to note that lamotrigine, although classified as a non-enzyme-inducing anticonvulsant, requires special consideration. While there is no evidence suggesting that the OCP directly affects epilepsy, there is evidence indicating that it reduces the levels of lamotrigine in the bloodstream. This reduction in lamotrigine levels could potentially compromise seizure control and increase the likelihood of experiencing seizures.

Angiotensin-converting enzyme (ACE) inhibitors are the primary cause of drug-induced angioedema in the UK and USA, mainly due to their widespread use. The incidence of angioedema caused by ACE inhibitors ranges from 0.1 to 0.7% among recipients, with evidence suggesting a consistent and persistent risk each year. Interestingly, individuals of African descent are approximately five times more likely to experience this adverse reaction.

The most common symptoms observed in patients with ACE inhibitor-induced angioedema include swelling of the lips, tongue, or face. However, another manifestation of this condition is episodic abdominal pain caused by intestinal angioedema. Notably, urticaria (hives) and itching are absent in these cases.

The underlying mechanism of ACE inhibitor-induced angioedema appears to involve the activation of the complement system or other pro-inflammatory cytokines, such as prostaglandins and histamine. These substances trigger rapid dilation of blood vessels and the accumulation of fluid, leading to edema.

Although less frequently associated with angioedema, other medications that may cause this condition include angiotensin-receptor blockers (ARBs), nonsteroidal anti-inflammatory drugs (NSAIDs), bupropion (e.g., Zyban and Wellbutrin), beta-lactam antibiotics, statins, and proton pump inhibitors.

Fortunately, most cases of drug-induced angioedema are mild and can be effectively managed by discontinuing the medication and prescribing oral antihistamines.

An elevated pH (normal range 7.34-7.45) suggests alkalosis. A low pCO2 (normal range 4.4-6.0 Kpa) indicates that the respiratory system is causing the alkalosis. The metabolic system, on the other hand, is not contributing to either alkalosis or acidosis as both the bicarbonate and base excess levels are within the normal ranges.

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.

The differences in anti-inflammatory activity among NSAIDs are minimal, but there is significant variation in how individuals respond to and tolerate these drugs. Approximately 60% of patients will experience a positive response to any NSAID, and those who do not respond to one may find relief with another. Pain relief typically begins shortly after taking the first dose, and a full analgesic effect is usually achieved within a week. However, it may take up to 3 weeks to see an anti-inflammatory effect, which may not be easily assessed. If desired results are not achieved within these timeframes, it is recommended to try a different NSAID.

NSAIDs work by reducing the production of prostaglandins through the inhibition of the enzyme cyclo-oxygenase. Different NSAIDs vary in their selectivity for inhibiting different types of cyclo-oxygenase. Selective inhibition of cyclo-oxygenase-2 is associated with a lower risk of gastrointestinal intolerance. Other factors also play a role in susceptibility to gastrointestinal effects, so the choice of NSAID should consider the incidence of gastrointestinal and other side effects.

Ibuprofen, a propionic acid derivative, possesses anti-inflammatory, analgesic, and antipyretic properties. It generally has fewer side effects compared to other non-selective NSAIDs, but its anti-inflammatory properties are weaker. For rheumatoid arthritis, doses of 1.6 to 2.4 g daily are required, and it may not be suitable for conditions where inflammation is prominent, such as acute gout.

Naproxen is often a preferred choice due to its combination of good efficacy and low incidence of side effects. However, it does have a higher occurrence of side effects compared to ibuprofen.

Ketoprofen and diclofenac have similar anti-inflammatory properties to ibuprofen but are associated with more side effects.

Indometacin has an action that is equal to or superior to naproxen, but it also has a high incidence of side effects, including headache, dizziness, and gastrointestinal disturbances.

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

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.

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.

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.

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.

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

Phyllocontin Continus contains aminophylline, which is a combination of theophylline and ethylenediamine. It is a bronchodilator that is commonly used to manage COPD and asthma.

In this case, the woman is showing symptoms of theophylline toxicity, which may have been triggered by the antibiotic prescribed for her urinary tract infection. Quinolone antibiotics, like ciprofloxacin, can increase the concentration of theophyllines in the blood, leading to toxicity.

There are other medications that can also interact with theophyllines. These include macrolide antibiotics such as clarithromycin, allopurinol, antifungals like ketoconazole, and calcium-channel blockers such as amlodipine. It is important to be aware of these interactions to prevent any potential complications.

Tricyclic antidepressant (TCA) overdose is a significant problem in cases of drug overdose and is one of the most common causes of fatal drug poisoning. Any overdose of amitriptyline that exceeds 10 mg/kg has the potential to be life-threatening. If the overdose surpasses 30 mg/kg, it will lead to severe toxicity, cardiotoxicity, and coma.

The toxic effects of TCAs are caused by various pharmacological actions. These include anticholinergic effects, direct blocking of alpha-adrenergic receptors, inhibition of noradrenaline reuptake at the preganglionic synapse, blockade of sodium channels, and blockade of potassium channels.

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.

In order to achieve satisfactory bronchodilation, most individuals require a plasma theophylline concentration of 10-20 mg/litre (55-110 micromol/litre). However, it is possible for a lower concentration to still be effective. Adverse effects can occur within the range of 10-20 mg/litre, and their frequency and severity increase when concentrations exceed 20 mg/litre.

To measure plasma theophylline concentration, a blood sample should be taken five days after starting oral treatment and at least three days after any dose adjustment. For modified-release preparations, the blood sample should typically be taken 4-6 hours after an oral dose (specific sampling times may vary, so it is advisable to consult local guidelines). If aminophylline is administered intravenously, a blood sample should be taken 4-6 hours after initiating treatment.

Sodium bicarbonate is recommended as a treatment for TCA overdose according to the latest guidelines from RCEM and NPIS in 2021. Previous editions also suggested using glucagon if IV fluids and sodium bicarbonate were ineffective in treating the overdose.

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.