Antipsychotics and antidepressants are drugs that are known to cause QT prolongation, which is a potentially dangerous heart rhythm abnormality. Similarly, SSRIs and other antidepressants are also associated with QT prolongation. On the other hand, beta-blockers like bisoprolol are used to shorten the QT interval and are considered as a treatment option for long QT syndrome. However, it’s important to note that sotalol, although classified as a beta blocker, acts differently by blocking potassium channels. This unique mechanism of action makes sotalol a class III anti-arrhythmic agent and may result in QT interval prolongation.

Further Reading:

Long QT syndrome (LQTS) is a condition characterized by a prolonged QT interval on an electrocardiogram (ECG), which represents abnormal repolarization of the heart. LQTS can be either acquired or congenital. Congenital LQTS is typically caused by gene abnormalities that affect ion channels responsible for potassium or sodium flow in the heart. There are 15 identified genes associated with congenital LQTS, with three genes accounting for the majority of cases. Acquired LQTS can be caused by various factors such as certain medications, electrolyte imbalances, hypothermia, hypothyroidism, and bradycardia from other causes.

The normal QTc values, which represent the corrected QT interval for heart rate, are typically less than 450 ms for men and less than 460ms for women. Prolonged QTc intervals are considered to be greater than these values. It is important to be aware of drugs that can cause QT prolongation, as this can lead to potentially fatal arrhythmias. Some commonly used drugs that can cause QT prolongation include antimicrobials, antiarrhythmics, antipsychotics, antidepressants, antiemetics, and others.

Management of long QT syndrome involves addressing any underlying causes and using beta blockers. In some cases, an implantable cardiac defibrillator (ICD) may be recommended for patients who have experienced recurrent arrhythmic syncope, documented torsades de pointes, previous ventricular tachyarrhythmias or torsades de pointes, previous cardiac arrest, or persistent syncope. Permanent pacing may be used in patients with bradycardia or atrioventricular nodal block and prolonged QT. Mexiletine is a treatment option for those with LQT3. Cervicothoracic sympathetic denervation may be considered in patients with recurrent syncope despite beta-blockade or in those who are not ideal candidates for an ICD. The specific treatment options for LQTS depend on the type and severity of the condition.

This patient exhibits clinical features that are consistent with the ingestion of a drug that blocks the action of the neurotransmitter acetylcholine in the central and peripheral nervous system. There are several anticholinergic drugs commonly used in clinical practice. Some examples include antihistamines like promethazine and diphenhydramine, typical and atypical antipsychotics such as haloperidol and quetiapine, anticonvulsants like carbamazepine, antidepressants like tricyclic antidepressants, and antispasmodics like hyoscine butylbromide. Other sources of anticholinergic effects can come from plants like datura species and certain mushrooms.

When someone ingests an anticholinergic drug, they may experience a toxidrome, which is characterized by an agitated delirium and various signs of acetylcholine receptor blockade in both the central and peripheral nervous system. The central inhibition leads to an agitated delirium, which is marked by fluctuating mental status, confusion, restlessness, visual hallucinations, picking at objects in the air, mumbling, slurred speech, disruptive behavior, tremor, myoclonus, and in rare cases, coma and seizures. The peripheral inhibition can cause dilated pupils, sinus tachycardia, dry mouth, hot and flushed skin, increased body temperature, urinary retention, and ileus.

In summary, the ingestion of an anticholinergic drug can result in a toxidrome characterized by an agitated delirium and various signs of central and peripheral acetylcholine receptor blockade. It is important to be aware of the potential effects of these drugs and to recognize the clinical features associated with their ingestion.

Sodium valproate is considered the most high-risk anti-epileptic drug during pregnancy. A recent review found that up to 40% of children born to women who took sodium valproate while pregnant experienced some form of adverse effect. These effects include a 1.5% risk of neural tube defects and an increased risk of cardiac, craniofacial, and limb defects. Additionally, there is a significant risk of neurodevelopmental problems in childhood.

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 trimester, 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 labor, premature closure of the fetal ductus arteriosus, and fetal kernicterus. However, low doses (e.g. 75 mg) do not pose a significant risk.

Benzodiazepines (e.g. diazepam): When given late in pregnancy, these drugs can cause 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 trimester, they can lead to fetal growth retardation.

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

Chloramphenicol: Use of this drug can result in gray baby syndrome.

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

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

Heparin: Maternal bleeding and thrombocytopenia are potential adverse outcomes.

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.

The use of tetracyclines is not recommended during pregnancy as it can have harmful effects on the developing fetus. When taken during the second half of pregnancy, tetracyclines may lead to permanent yellow-grey discoloration of the teeth and enamel hypoplasia. Children affected by this may also be more prone to cavities. Additionally, tetracyclines have been associated with congenital defects, problems with bone growth, and liver toxicity in pregnant women.

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

ACE inhibitors (e.g. ramipril): If taken in the second and third trimesters, ACE inhibitors can cause reduced blood flow, kidney failure, and a condition called oligohydramnios.

Aminoglycosides (e.g. gentamicin): Aminoglycosides can cause ototoxicity, leading to hearing loss in the fetus.

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

Benzodiazepines (e.g. diazepam): When taken late in pregnancy, benzodiazepines can cause respiratory depression in the newborn and a withdrawal syndrome.

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

Carbamazepine: Carbamazepine has been associated with a condition called hemorrhagic disease of the newborn and an increased risk of neural tube defects.

Chloramphenicol: Chloramphenicol can cause a condition known as grey baby syndrome in newborns.

Corticosteroids: If taken in the first trimester, corticosteroids may increase the risk of orofacial clefts in the fetus.

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

Finasteride: Pregnant women should avoid handling finasteride tablets as the drug can be absorbed through the skin and affect the development of male sex organs in the fetus.

Haloperidol: If taken during the first trimester, this medication may increase the risk of limb malformations. If taken during the third trimester, it can lead to an increased risk of extrapyramidal symptoms in the newborn.

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.

The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is characterized by the presence of low sodium levels and low osmolality due to the inappropriate and continuous release or action of the hormone, despite normal or increased blood volume. This leads to a decreased ability to excrete water.
There are several factors that can cause SIADH, with carbamazepine being a well-known example. These causes can be grouped into different categories. One category is CNS damage, which includes conditions like meningitis and subarachnoid hemorrhage. Another category is malignancy, with small-cell lung cancer being a common cause. Certain drugs, such as carbamazepine, SSRIs, amitriptyline, and morphine, can also trigger SIADH. Infections, such as pneumonia, lung abscess, and brain abscess, are another potential cause. Lastly, endocrine disorders like hypothyroidism can contribute to the development of SIADH.

Glucagon may be an option for individuals experiencing anaphylaxis while taking beta blockers. However, it should not be chosen over Adrenaline as the primary treatment. Glucagon stimulates the production of cyclic AMP, which helps to increase heart contractility and heart rate, both of which are necessary during anaphylaxis. It is important to note that rapid administration of glucagon may lead to adverse effects such as nausea and vomiting.

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

Isoniazid has the potential to induce acute hepatitis, but it is not considered a known cause of cholestatic jaundice. On the other hand, there are several drugs that have been identified as culprits for cholestatic jaundice. These include nitrofurantoin, erythromycin, cephalosporins, verapamil, NSAIDs, ACE inhibitors, tricyclic antidepressants, phenytoin, azathioprine, carbamazepine, oral contraceptive pills, diazepam, ketoconazole, and tamoxifen. It is important to be aware of these medications and their potential side effects in order to ensure patient safety.

Calcium-channel blocker overdose is a serious condition that can be life-threatening. The 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 are important for the functioning of cardiac myocytes, vascular smooth muscle cells, and islet beta-cells.

When managing a patient with calcium-channel blocker overdose, it is crucial to follow the standard ABC approach for resuscitation. If there is a risk of life-threatening toxicity, early intubation and ventilation should be considered. Invasive blood pressure monitoring is also necessary if hypotension and shock are developing.

The specific treatments for calcium-channel blocker overdose primarily focus on supporting the cardiovascular system. These treatments include:

1. Fluid resuscitation: Administer up to 20 mL/kg of crystalloid solution.

2. Calcium administration: This can temporarily increase blood pressure and heart rate. Options include 10% calcium gluconate (60 mL IV) or 10% calcium chloride (20 mL IV) via central venous access. Repeat boluses can be given up to three times, and a calcium infusion may be necessary to maintain serum calcium levels above 2.0 mEq/L.

3. Atropine: Consider administering 0.6 mg every 2 minutes, up to a total of 1.8 mg. However, atropine is often ineffective in these cases.

4. High dose insulin – euglycemic therapy (HIET): The use of HIET in managing cardiovascular toxicity has evolved. It used to be a last-resort measure, but early administration is now increasingly recommended. This involves giving a bolus of short-acting insulin (1 U/kg) and 50 mL of 50% glucose IV (unless there is marked hyperglycemia). Therapy should be continued with a short-acting insulin/dextrose infusion. Glucose levels should be monitored frequently, and potassium should be replaced if levels drop below 2.5 mmol/L.

5. Vasoactive infusions: Catecholamines such as dopamine, adrenaline, and/or noradrenaline can be titrated to achieve the desired inotropic and chronotropic effects.

6. Sodium bicarbonate: Consider using sodium bicarbonate in cases where a severe metabolic acidosis develops.

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)

For asymptomatic patients, it is recommended to measure salicylate levels 4 hours after ingestion. However, if the patient is experiencing symptoms, the initial levels should be taken 2 hours after ingestion. In this case, the levels should be monitored every 2-3 hours until a decrease is observed.

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.

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.

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.

The primary symptom typically associated with carbon monoxide poisoning is a headache.

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.

Spironolactone is a medication used to treat conditions such as congestive cardiac failure, hypertension, hepatic cirrhosis with ascites and edema, and Conn’s syndrome. It functions as a competitive aldosterone receptor antagonist, primarily working in the distal convoluted tubule. In this area, it hinders the reabsorption of sodium ions and enhances the reabsorption of potassium ions. Spironolactone is commonly known as a potassium-sparing diuretic.

The main side effect of spironolactone is hyperkalemia, particularly when renal impairment is present. In severe cases, hyperkalemia can be life-threatening. Additionally, there is a notable occurrence of gastrointestinal disturbances, with nausea and vomiting being the most common. Women may experience menstrual disturbances, while men may develop gynecomastia, both of which are attributed to the antiandrogenic effects of spironolactone.

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.

Activated charcoal prevents the absorption of poisons by absorbing them onto its surface through weak electrostatic forces.

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 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.

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.

Anticholinergic drugs work by blocking the effects of acetylcholine, a neurotransmitter, in both the central and peripheral nervous systems. These drugs are commonly used in clinical practice and include antihistamines, typical and atypical antipsychotics, anticonvulsants, antidepressants, antispasmodics, antiemetics, antiparkinsonian agents, antimuscarinics, and certain plants. When someone ingests an anticholinergic drug, they may experience a toxidrome, which is characterized by an agitated delirium and various signs of acetylcholine receptor blockade in the central and peripheral systems.

The central effects of anticholinergic drugs result in an agitated delirium, which is marked by fluctuating mental status, confusion, restlessness, visual hallucinations, picking at objects in the air, mumbling, slurred speech, disruptive behavior, tremor, myoclonus, and in rare cases, coma or seizures. On the other hand, the peripheral effects can vary and may include dilated pupils, sinus tachycardia, dry mouth, hot and flushed skin, increased body temperature, urinary retention, and ileus.

The most commonly observed change in the electrocardiogram (ECG) during a tricyclic antidepressant (TCA) overdose is sinus tachycardia. Additionally, other ECG changes that can be seen in TCA overdose include prolongation of the PR interval, broadening of the QRS complex, prolongation of the QT interval, and the occurrence of ventricular arrhythmias in cases of severe toxicity. The cardiotoxic effects of TCAs are caused by the blocking of sodium channels, which leads to broadening of the QRS complex, and the blocking of potassium channels, which results in prolongation of the QT interval. The severity of the QRS broadening is associated with adverse events: a QRS duration greater than 100 ms is predictive of seizures, while a QRS duration greater than 160 ms is predictive of ventricular arrhythmias.

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.

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.

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.

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.

Cytochrome p450 enzyme inducers have the ability to hinder the effects of warfarin, leading to a decrease in INR levels. To remember the commonly encountered cytochrome p450 enzyme inducers, the mnemonic PC BRASS can be utilized. Each letter in the mnemonic represents a specific inducer: P for Phenytoin, C for Carbamazepine, B for Barbiturates, R for Rifampicin, A for Alcohol (chronic ingestion), S for Sulphonylureas, and S for Smoking. These inducers can have an impact on the effectiveness of warfarin and should be taken into consideration when prescribing or using this medication.

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

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.