Treatment of acute organophosphorus poisoning includes all of the following EXCEPT:

Correct Answer: D

Rationale: The correct answer is D: Intravenous methacholine. Methacholine is a parasympathomimetic drug that would worsen the symptoms of organophosphorus poisoning by further stimulating the cholinergic receptors. Intravenous atropine is used to counteract the excessive cholinergic stimulation. Decontamination is crucial to remove any remaining poison from the skin or gastrointestinal tract. Artificial respiration and aspiration of secretions help manage respiratory distress caused by the poisoning.

Correct Answer: C

Rationale: The correct answer is C: Pilocarpine. Parasympatholytic drugs inhibit the parasympathetic nervous system. Pilocarpine, on the other hand, is a parasympathomimetic drug that stimulates the parasympathetic nervous system. Hyoscine, Atropine, and Ipratropium are all parasympatholytic drugs that block the effects of the parasympathetic nervous system. Therefore, pilocarpine is the exception in this list.

Correct Answer: D

Rationale: The correct answer is D: Tropicamide. Tropicamide is a short-acting cycloplegic and mydriatic drug commonly used in ophthalmology. It acts quickly, providing temporary dilation of the pupil and relaxation of the ciliary muscle for refraction assessment. Atropine (A) is a long-acting cycloplegic, not short-acting. Homatropine (B) and Hyoscine (C) are also longer-acting drugs compared to Tropicamide. Therefore, D is the correct answer for its rapid onset and short duration of action in dilating the pupil and paralyzing accommodation.

Correct Answer: D

Rationale: The correct answer is D: Beta-adrenergic antagonists. Beta-blockers can mask the typical signs and symptoms of hypoglycemia such as tremors, palpitations, and sweating by inhibiting the adrenergic response to low blood sugar levels. Other choices (A, B, C) are incorrect as they do not have the same mechanism of action in masking hypoglycemic reactions in diabetic patients.

Correct Answer: C

Rationale: The correct answer is C: Phenylephrine. Phenylephrine is a sympathomimetic drug that stimulates the sympathetic nervous system, leading to vasoconstriction and increased heart rate. In contrast, choices A, B, and D all work to depress sympathetic activity by different mechanisms. Clonidine is an alpha-2 adrenergic agonist that decreases sympathetic outflow. Reserpine inhibits the storage of norepinephrine, leading to decreased sympathetic activity. Labetalol is a non-selective beta blocker that blocks beta-adrenergic receptors, reducing sympathetic effects. Therefore, Phenylephrine is the only drug among the options that does not depress sympathetic activity.