Which of the following is not a parasympatholytic drug:

Correct Answer: D

Rationale: The correct answer is D, Edrophonium, because it is not a parasympatholytic drug but rather a parasympathomimetic drug used for diagnosing myasthenia gravis. Atropine (A), Propantheline (B), and Pirenzepine (C) are all parasympatholytic drugs that inhibit the parasympathetic nervous system by blocking acetylcholine receptors. Atropine is a nonselective muscarinic receptor antagonist, Propantheline is an antimuscarinic drug used to treat gastrointestinal disorders, and Pirenzepine is a selective M1 receptor antagonist used to reduce gastric acid secretion. Therefore, D is the correct choice as it does not belong to the category of parasympatholytic drugs.

Correct Answer: A

Rationale: Neostigmine is the correct choice for treating myasthenia gravis as it is an acetylcholinesterase inhibitor that increases acetylcholine levels, improving muscle strength. Pilocarpine is a muscarinic agonist used for glaucoma. Succinylcholine is a depolarizing neuromuscular blocker used for intubation. Tubocurarine is a non-depolarizing neuromuscular blocker.

Correct Answer: D

Rationale: Adrenaline is a sympathomimetic drug that acts on adrenergic receptors. In acute situations like allergic reactions, bronchial asthma, and heart block, adrenaline can be beneficial due to its bronchodilator and vasoconstrictor effects. However, in angina pectoris, which is caused by reduced blood flow to the heart muscle, the vasoconstrictor effect of adrenaline can worsen the condition by increasing the workload of the heart. Therefore, adrenaline should not be used in angina pectoris.

Correct Answer: C

Rationale: Rationale: Labetalol is a non-selective beta-blocker that reduces cardiac contractility by blocking beta-1 receptors and inhibits sympathetic-mediated vasoconstriction by blocking alpha-1 receptors. Albuterol (A) is a beta-2 agonist, which increases cardiac contractility. Atropine (B) is a muscarinic antagonist, which increases heart rate and does not affect vasoconstriction. Isoproterenol (D) is a non-selective beta agonist, which increases cardiac contractility and vasodilation. Thus, C (Labetalol) is the only drug that can lower blood pressure by both mechanisms.

Correct Answer: B

Rationale: Step 1: MAO inhibitors prevent the breakdown of neurotransmitters like norepinephrine. Step 2: Pseudoephedrine stimulates the release of norepinephrine. Step 3: The combination can lead to excessive norepinephrine, causing hypertension and potential stroke. Therefore, the likely outcome when a patient taking an MAO inhibitor also takes pseudoephedrine is a hypertensive crisis and possible stroke (Choice B). Summary: - Choice A (acute bronchospasm/asthma due to ACh release from the adrenal medulla) is incorrect because pseudoephedrine does not directly cause this response. - Choice C (heart rate and contractile force would drop significantly and quickly) is incorrect as pseudoephedrine tends to increase heart rate and blood pressure. - Choice D (the cold symptoms would quickly get worse - increased secretions) is incorrect as pseudoephedrine is a decongestant and would not worsen cold symptoms