Group 7 Flashcards
(25 cards)
What is the mechanism of magnesium sulphate toxicity?
Acts as a calcium antagonist, inhibiting calcium influx → neuromuscular blockade, CNS depression, and neurotransmitter interference.
List three symptoms of magnesium sulphate overdose.
- Respiratory depression.
- Muscle weakness/lethargy.
- Cardiac arrhythmias.
What is the antidote for magnesium toxicity, and how is it administered?
Calcium gluconate (IV).
What preventive measures reduce magnesium sulphate toxicity risk?
Monitor serum levels in IV therapy, avoid excessive laxative use, and caution in renal impairment.
How does methylene blue paradoxically worsen methemoglobinemia at high doses?
- At high doses it oxidizes hemoglobin → increased methemoglobin levels.
- Inhibits guanylate cyclase → Reducing cGMP levels and causing vascular smooth muscle contraction
Why is methylene blue dangerous in G6PD-deficient patients?
It causes oxidative stress, triggering hemolysis.
‘What are key treatments for methylene blue toxicity?
- Discontinue use.
- Oxygen therapy.
- Blood transfusion (severe hemolysis).
- Activated charcoal (if ingested).
Name two symptoms of methylene blue overdose.
Skin discoloration (blue/green), hemolysis, seizures.
What enzyme do organophosphates/carbamates inhibit, and what symptoms result?
Acetylcholinesterase inhibition → muscarinic (salivation, lacrimation) and nicotinic (muscle twitching) effects.
How do pyrethroids differ from organochlorines in toxicity?
- Pyrethroids: Disrupt sodium channels → mild skin/respiratory irritation.
- Organochlorines: Persist in environment disrupt nerve function → long-term neurological effects.
What antidotes are used for organophosphate poisoning?
- Atropine (blocks muscarinic receptors).
- Pralidoxime (2-PAM) (reactivates acetylcholinesterase).
What are three preventive measures for insecticide exposure?
- Use PPE (gloves, masks).
- Follow label instructions.
- Secure storage away from children.
Why is dialysis used in severe magnesium sulphate toxicity?
To rapidly remove magnesium, especially in renal impairment.
What is a critical precaution for methylene blue use?
Avoid in G6PD deficiency due to hemolysis risk.
How do organochlorines affect the nervous system?
Disrupt nerve function → tremors, dizziness, convulsions.
How do organochlorines differ from other insecticides in terms of environmental impact and toxicity?
They persist in the environment and cause long-term neurotoxicity (e.g., tremors, convulsions) due to nerve function disruption.
Name two examples of organochlorine insecticides.
DDT, lindane.
What is the dosing regimen for atropine in organophosphate poisoning?
1–2 mg IV every 5–15 minutes until muscarinic symptoms (e.g., salivation, bronchospasm) resolve.
How is pralidoxime administered for acetylcholinesterase reactivation?
1–2 g IV over 15–30 minutes, followed by continuous infusion if needed.
How does methylene blue inhibit guanylate cyclase, and what clinical effect does this cause?
Reduces cyclic GMP → vascular smooth muscle contraction, exacerbating hypertension or ischemia.
Give an example of a clinical scenario requiring methylene blue.
Managing ifosfamide-induced encephalopathy or severe methemoglobinemia (e.g., from nitrate poisoning).
What precaution is unique to pyrethroid insecticide handling?
Ensure adequate ventilation to avoid respiratory irritation from aerosolized particles.
Why are organochlorines banned in many countries despite their efficacy?
Due to environmental persistence and bioaccumulation in the food chain.
What supportive measure is critical for magnesium sulphate-induced respiratory depression?
Mechanical ventilation and fluid-electrolyte balance.
