Pesticides Poisoning Quiz: Organophosphates & Carbamates

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Questions and Answers

What is one factor that can lead to increased absorption through the skin?

Broken skin (correct)

Cold environmental temperature

Apply oil-based products

Low humidity

How does high environmental temperature affect absorption via the skin?

It has no effect on absorption

It reduces the skin's permeability

It increases the absorption rate (correct)

It only affects dry skin

What skin condition mentioned can facilitate increased absorption?

Acne

Dermatitis (correct)

Eczema

Psoriasis

Which environmental condition is least likely to enhance dermal absorption?

Low atmospheric pressure Signup and view all the answers

What effect does an increase in skin temperature have on absorption through the skin?

Enhances absorption rates Signup and view all the answers

What type of receptors are found at autonomic ganglia and neuromuscular junctions?

Nicotinic receptors Signup and view all the answers

Which of the following correctly describes the function of autonomic ganglia?

They transmit signals from the CNS to the peripheral nervous system. Signup and view all the answers

Which system primarily utilizes nicotinic receptors?

Central nervous system (CNS) Signup and view all the answers

What distinguishes nicotinic receptors from other receptor types?

They can be activated by acetylcholine. Signup and view all the answers

Which location is associated with the presence of nicotinic receptors?

Neuromuscular junctions Signup and view all the answers

What is a common side effect experienced at therapeutic doses?

Transient dizziness Signup and view all the answers

What can rapid IV administration lead to?

Sudden cardiac and respiratory issues Signup and view all the answers

Which side effect is NOT related to therapeutic doses?

Severe vomiting Signup and view all the answers

What is a safety concern when administering medication via rapid IV?

Risk of sudden cardiac and respiratory events Signup and view all the answers

Which of the following side effects indicates a need for caution during rapid IV administration?

Sudden cardiac and respiratory distress Signup and view all the answers

What physiological response is indicated by diaphoresis?

Stimulation of sweat glands Signup and view all the answers

Which condition can be a consequence of neuromuscular junction disruption?

Skeletal muscle weakness Signup and view all the answers

What cardiovascular symptoms can be accidentally observed in some cases?

Hypertension and tachycardia Signup and view all the answers

What serious complication can arise from neuromuscular junction issues?

Respiratory arrest Signup and view all the answers

Which symptom is not typically associated with neuromuscular junction issues?

Increased muscle tone Signup and view all the answers

Which of the following symptoms is associated with the use of dumbbells?

Urination and defecation Signup and view all the answers

What visual disturbances may occur as a result of using dumbbells?

Miosis and blurred vision Signup and view all the answers

Which of the following combinations of symptoms relate to dumbbells?

Urination, defecation, and miosis Signup and view all the answers

What is a potential effect on the digestive system when using dumbbells?

Urination and defecation Signup and view all the answers

Which of the following is NOT a symptom associated with dumbbells?

Chest pain Signup and view all the answers

What is the loading dose for an adult experiencing severe toxicity?

3-5 mg IV Signup and view all the answers

Which dose is recommended for an adult with mild to moderate toxicity?

1-2 mg IV Signup and view all the answers

What is the higher end of the loading dose range for adults?

5 mg IV Signup and view all the answers

What is the correct loading dose range for adults?

1-2 mg IV or 3-5 mg IV Signup and view all the answers

For an adult with moderate toxicity, which dose is appropriate?

1-2 mg IV Signup and view all the answers

Study Notes

Pesticides Poisoning (Organophosphates & Carbamates)

Learning Objectives: Students should understand the circumstances, toxicokinetics, mechanism, clinical picture, and treatment of organophosphorus compound (OPC) poisoning, and compare it with carbamate poisoning. Pearls and pitfalls concerning OPC poisoning are also key.

Circumstances of Poisoning

Accidental: Poisoning occurs during pesticide handling (manufacturing, spraying), drinking contaminated water or food, or co-ingesting OPCs with cocaine.
Suicidal: OPC poisoning is a common method for suicide due to ease of access and rapid lethality.
Homicidal: Rare, potentially due to the distinctive "garlic" odor of OPCs.

Toxicokinetics of OPCs

Absorption: OPCs are rapidly absorbed via respiratory, gastrointestinal, conjunctiva, dermal, and mucous membrane routes, with respiratory absorption being the fastest. Absorption is enhanced by broken skin or high environmental temperatures.
Distribution: OPCs distribute throughout the body and cross the blood-brain barrier; they are highly lipid-soluble and can accumulate in fatty tissues, which can lead to prolonged toxicity.
Metabolism: OPCs are mainly metabolized in the liver by cytochrome P-450 enzymes.
Excretion: OPCs are excreted through urine and stool.

Mechanism of OPC Toxicity

Cholinesterase Inhibition: OPCs irreversibly inhibit cholinesterase, an enzyme crucial for breaking down acetylcholine (Ach), resulting in its accumulation. The build-up causes initial stimulation of postganglionic parasympathetic nerve endings, autonomic ganglia, and neuromuscular junctions, followed by depression of impulse transmission.
Consequences: The cholinergic syndrome (DUMBELLS) and nicotinic effects are symptomatic of cholinesterase inhibition.

Clinical Picture of OPC Poisoning

Muscarinic Effects (DUMBELLS): Diarrhea, Urination, Miosis, Bradycardia, Bronchospasm, Lacrimation, and Excessive secretions (sweating, salivation).
Nicotinic Effects: Prolonged QT interval (PVT), torsades de pointes, diaphoresis, hypertension, tachycardia, skeletal muscle fasciculations, weakness, paralysis, and respiratory arrest.
CNS Effects: Anxiety, insomnia, confusion, ataxia, coma, seizures (more common in children), and respiratory and circulatory depression.

Treatment of OPC Poisoning

Emergency & Supportive Measures (ABC): Airway and breathing management, frequent suctioning, respiratory support, intubation (if needed), control of fluid loss, and treatment of seizures (using diazepam or phenobarbital).
Decontamination: Avoid further exposure. Gastric decontamination may not be beneficial due to rapid absorption; prevent contact with skin or contaminated clothes and items. Use soap and water, then ethyl alcohol for thorough cleaning.
Physiological Antidotes:
Atropine: A competitive Ach antagonist, reversing muscarinic and CNS effects, but not nicotinic effects. Dosage and duration of action vary depending on toxicity level. Side effects/high doses include peripheral anticholinergic effects (tachycardia, flushed skin, mydriasis, urine retention, hallucination).
Oximes: Reactivate cholinesterase, detoxify OPC molecules. Correct nicotinic manifestations. Used in cases of suspected or confirmed poisoning, or with significant atropine requirement or neuromuscular weakness. Specifically, obidoxime (toxogonin) used outside the USA.

Carbamate Poisoning

Difference: Carbamates are acetylcholinesterase inhibitors similar to OPCs but have a shorter duration of action; binding is reversible.
Clinical Picture: Similiar to OPCs, but less severe and shorter-lasting manifestations. Lower risk of CNS manifestations compared to OPC, because carbamates have poorer BBB penetration.
Treatment: Oximes are generally not indicated because the carbamate effects resolve spontaneously.

Pearls & Pitfalls

Prognosis: Quickly recognized and treated OPC poisoning typically has a good outcome. Untreated cases may lead to respiratory failure and potentially, death within 24 hours.
Observation: Delayed onset symptoms are possible, especially with fat-soluble agents. Patients require observation (12–24 hours, to account for delayed onset).
Return to Work: Farmers and workers may not return to work until levels of cholinesterase (CHE) return to over 75% normal.
Intubation: If intubation is needed, avoid succinylcholine and mivacurium, as these are metabolized by pseudocholinesterase which can prolong paralysis by over 24 hours.

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Description

Test your knowledge on the circumstances, toxicokinetics, and treatment of organophosphate compound poisoning as well as carbamate poisoning. Understand the differences in clinical presentations and learn about the potential pitfalls in managing these conditions.