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.

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

Further Reading:

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

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

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

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

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

This individual has developed Dupuytren’s contracture, which is a hand deformity characterized by a fixed flexion caused by palmar fibromatosis. The only anticonvulsant treatment believed to be connected to the development of Dupuytren’s contracture is phenytoin. Additionally, other conditions associated with its occurrence include liver cirrhosis, diabetes mellitus, alcoholism, and trauma.

The standard drug regimen for tuberculosis is generally safe to use during pregnancy, with the exception of streptomycin which should be avoided. However, the use of isoniazid during pregnancy has been associated with potential risks such as liver damage in the mother and the possibility of neuropathy and seizures in the newborn.

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

ACE inhibitors (e.g. ramipril): If taken during the second and third trimesters, these medications can lead to reduced blood flow, kidney failure, and a condition called oligohydramnios.

Aminoglycosides (e.g. gentamicin): These drugs can cause ototoxicity, resulting in hearing loss in the baby.

Aspirin: High doses of aspirin can increase the risk of 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, these medications can cause respiratory depression in the baby and lead to a withdrawal syndrome.

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

Carbamazepine: This medication can increase the risk of hemorrhagic disease in the newborn and neural tube defects.

Chloramphenicol: Use of this drug in newborns can lead to a condition known as grey baby syndrome.

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

Danazol: When taken during the first trimester, this medication can cause masculinization of the female fetuses genitals.

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

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.

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

Activated charcoal is a 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.

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.

Tetracycline antibiotics, such as tetracycline and doxycycline, have the potential to cause staining on permanent teeth while they are still forming beneath the gum line. This staining occurs when the drug becomes calcified within the tooth during its development. It is important to note that children are vulnerable to tetracycline-related tooth staining until approximately the age of 8. Additionally, pregnant women should avoid taking tetracycline as it can affect the development of teeth in the unborn child.

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.

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.

Statins, although generally safe and well-tolerated, can cause myopathy and myotoxicity. This range of muscle-related side effects can vary from mild muscle pain to the most severe case of rhabdomyolysis, which can lead to kidney failure, blood clotting issues, and even death.

The different levels of myotoxicity associated with statins are as follows:
– Myalgia: muscle symptoms without an increase in creatine kinase (CK) levels.
– Asymptomatic myopathy: elevated CK levels without muscle symptoms.
– Myositis: muscle symptoms with CK levels elevated less than 10 times the upper limit of normal.
– Rhabdomyolysis: muscle symptoms with CK levels elevated more than 10 times the upper limit of normal, potentially leading to myoglobinuria (presence of myoglobin in urine) and renal failure.

Most statins are broken down by the cytochrome P450 enzyme system. When taken with drugs that strongly inhibit this system, the concentration of statins in the blood can significantly increase. This, in turn, raises the risk of myopathy. A well-known example of this is the combination of statins with macrolide antibiotics like erythromycin and clarithromycin. Co-prescribing these drugs with statins has been linked to a higher risk of myopathy, hospitalization due to rhabdomyolysis, acute kidney injury, and increased mortality rates.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.

Digoxin-specific antibody (DigiFab) is an antidote used to counteract digoxin overdose. It is a purified and sterile preparation of digoxin-immune ovine Fab immunoglobulin fragments. These fragments are derived from healthy sheep that have been immunized with a digoxin derivative called digoxin-dicarboxymethoxylamine (DDMA). DDMA is a digoxin analogue that contains the essential cyclopentanoperhydrophenanthrene: lactone ring moiety coupled to keyhole limpet hemocyanin (KLH).

DigiFab has a higher affinity for digoxin compared to the affinity of digoxin for its sodium pump receptor, which is believed to be the receptor responsible for its therapeutic and toxic effects. When administered to a patient who has overdosed on digoxin, DigiFab binds to digoxin molecules, reducing the levels of free digoxin in the body. This shift in equilibrium away from binding to the receptors helps to reduce the cardiotoxic effects of digoxin. The Fab-digoxin complexes are then eliminated from the body through the kidney and reticuloendothelial system.

The indications for using DigiFab in cases of acute and chronic digoxin toxicity are summarized below:

Acute digoxin toxicity:
– Cardiac arrest
– Life-threatening arrhythmia
– Potassium level >5 mmol/l
– Ingestion of >10 mg of digoxin (in adults)
– Ingestion of >4 mg of digoxin (in children)
– Digoxin level >12 ng/ml

Chronic digoxin toxicity:
– Cardiac arrest
– Life-threatening arrhythmia
– Significant gastrointestinal symptoms
– Symptoms of digoxin toxicity in the presence of renal failure

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.

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.

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.

Tinnitus is often seen as an early indication of salicylate toxicity, which occurs when there is an excessive use of salicylate. Another common symptom is feeling nauseous and/or vomiting. In the initial stages of a salicylate overdose, individuals may experience respiratory alkalosis, which is caused by the direct stimulation of the respiratory centers in the medulla by salicylate. This leads to hyperventilation and the elimination of carbon dioxide, resulting in alkalosis. As the body metabolizes salicylate, a metabolic acidosis may develop.

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.

Activated charcoal is a commonly utilized substance for decontamination in cases of poisoning. Its main function is to attract and bind 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. This powder is created by subjecting carbonaceous matter to high heat, a process known as pyrolysis, and then concentrating it with a solution of zinc chloride. Through this process, the activated charcoal develops a complex network of pores, providing it with a large surface area of approximately 3,000 m2/g. This extensive surface area allows it to effectively hinder the absorption of the harmful toxin by up to 50%.

The typical dosage for adults is 50 grams, while children are usually given 1 gram per kilogram of body weight. Activated charcoal can be administered orally or through a nasogastric tube. It is crucial to administer it within one hour of ingestion, and if necessary, a second dose may be repeated after one hour.

Digoxin-specific antibody (DigiFab) is an antidote used to counteract digoxin overdose. It is a purified and sterile preparation of digoxin-immune ovine Fab immunoglobulin fragments. These fragments are derived from healthy sheep that have been immunized with a digoxin derivative called digoxin-dicarboxymethoxylamine (DDMA). DDMA is a digoxin analogue that contains the essential cyclopentanoperhydrophenanthrene: lactone ring moiety coupled to keyhole limpet hemocyanin (KLH).

DigiFab has a higher affinity for digoxin compared to the affinity of digoxin for its sodium pump receptor, which is believed to be the receptor responsible for its therapeutic and toxic effects. When administered to a patient who has overdosed on digoxin, DigiFab binds to digoxin molecules, reducing the levels of free digoxin in the body. This shift in equilibrium away from binding to the receptors helps to reduce the cardiotoxic effects of digoxin. The Fab-digoxin complexes are then eliminated from the body through the kidney and reticuloendothelial system.

The indications for using DigiFab in cases of acute and chronic digoxin toxicity are summarized below:

Acute digoxin toxicity:
– Cardiac arrest
– Life-threatening arrhythmia
– Potassium level >5 mmol/l
– Ingestion of >10 mg of digoxin (in adults)
– Ingestion of >4 mg of digoxin (in children)
– Digoxin level >12 ng/ml

Chronic digoxin toxicity:
– Cardiac arrest
– Life-threatening arrhythmia
– Significant gastrointestinal symptoms
– Symptoms of digoxin toxicity in the presence of renal failure

Beta-blockers, like bisoprolol, and verapamil have a strong negative effect on the force of ventricular contraction. When these medications are taken together, they can significantly reduce ventricular contraction and lead to a slow heart rate, known as bradycardia. Additionally, the risk of developing AV block is increased. In certain situations, this combination can result in severe low blood pressure or even a complete absence of heart rhythm, known as asystole. Therefore, it is important to avoid using these medications together to prevent these potentially dangerous effects.

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.

Glucagon is the preferred initial treatment for beta-blocker poisoning when there are symptoms of slow heart rate and low blood pressure.

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.

Potassium-sparing diuretics, like spironolactone and eplerenone, can raise the chances of developing hyperkalemia when taken alongside ACE inhibitors, such as ramipril, and angiotensin-II receptor antagonists, like losartan. Additionally, eplerenone can also heighten the risk of hypotension when co-administered with losartan.

For more information, please refer to the BNF section on losartan interactions.

Patients who have taken an overdose of tricyclic antidepressants (TCAs) should not be given phenytoin.

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.

Verapamil is a type of calcium-channel blocker that is commonly used to treat irregular heart rhythms and chest pain. It is important to note that verapamil should not be taken at the same time as beta-blockers like atenolol. This is because when these medications are combined, they can have a negative impact on the heart’s ability to contract and its heart rate. This can lead to low blood pressure, slow heart rate, problems with the electrical signals in the heart, heart failure, and even a pause in the heart’s normal rhythm. However, the other medications mentioned in this question can be safely used together with beta-blockers.

Amiodarone is a medication that can have numerous harmful side effects, making it crucial to conduct a comprehensive clinical assessment before starting treatment with it. Some of the side effects associated with amiodarone include corneal microdeposits, photosensitivity, nausea, sleep disturbance, hyperthyroidism, hypothyroidism, acute hepatitis and jaundice, peripheral neuropathy, lung fibrosis, QT prolongation, and optic neuritis (although this is very rare). If optic neuritis occurs, immediate discontinuation of amiodarone is necessary to prevent the risk of blindness.

The majority of patients taking amiodarone experience corneal microdeposits, but these typically resolve after treatment is stopped and rarely affect vision. Amiodarone has a chemical structure similar to thyroxine and can bind to the nuclear thyroid receptor, leading to both hypothyroidism and hyperthyroidism. However, hypothyroidism is more commonly observed, affecting around 5-10% of patients.

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.

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

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

Activated charcoal is a commonly utilized substance for decontamination in cases of poisoning. Its main function is to attract and bind 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. This powder is created by subjecting carbonaceous matter to high heat, a process known as pyrolysis, and then concentrating it with a solution of zinc chloride. Through this process, the activated charcoal develops a complex network of pores, providing it with a large surface area of approximately 3,000 m2/g. This extensive surface area allows it to effectively hinder the absorption of the harmful toxin by up to 50%.

The typical dosage for adults is 50 grams, while children are usually given 1 gram per kilogram of body weight. Activated charcoal can be administered orally or through a nasogastric tube. It is crucial to administer it within one hour of ingestion, and if necessary, a second dose may be repeated after one hour.

Gentamicin is an antibiotic belonging to the aminoglycoside class. It works by binding to the 30S subunit of the ribosome in bacteria, thereby preventing the binding of aminoacyl-tRNA and ultimately inhibiting the initiation of protein synthesis.

The two most significant side effects associated with gentamicin are hearing loss and reversible nephrotoxicity. These side effects are directly related to the dosage of the medication and are more commonly observed in elderly individuals.

Hearing loss occurs due to damage to the vestibular apparatus located in the inner ear. On the other hand, nephrotoxicity is caused by the inhibition of protein synthesis in renal cells. This inhibition leads to necrosis of the cells in the proximal convoluted tubule and results in a condition known as acute tubular necrosis.

In summary, gentamicin mechanism of action and side effects, such as hearing loss and reversible nephrotoxicity, are closely linked to its interaction with the bacterial ribosome and its impact on protein synthesis. These effects are particularly prevalent in the elderly population.