During surgery, we administer hexamethonium to an anesthetized patient. Which of the following effects should you expect in response to this drug?

Correct Answer: D

Rationale: The correct answer is D: Vasodilation. Hexamethonium is a ganglionic blocking agent that blocks nicotinic receptors in autonomic ganglia, leading to vasodilation due to inhibition of sympathetic vasoconstrictor tone. This causes a decrease in blood pressure. A: Bradycardia is not a direct effect of hexamethonium. B: Increased GI motility and defecation are not expected effects of hexamethonium. C: Increased salivary secretions are not directly affected by hexamethonium. In summary, the correct answer is D because hexamethonium causes vasodilation by blocking nicotinic receptors in autonomic ganglia, leading to a decrease in blood pressure.

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: B

Rationale: Salbutamol is a beta2-adrenergic agonist that relaxes smooth muscles in the airways, making it an effective treatment for bronchial asthma by relieving bronchospasm and improving airflow. It is not used for angina pectoris, hypertension, or cardiac arrhythmias as these conditions do not involve bronchial constriction.

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.