What significant side effect of terazosin should the doctor warn a 69-year-old male patient about?

Correct Answer: B

Rationale: The correct answer is B: Postural hypotension. Terazosin is an alpha-1 blocker used to treat hypertension and BPH. Postural hypotension is a common side effect due to vasodilation, causing a sudden drop in blood pressure when changing positions. This side effect can lead to dizziness, fainting, and falls, especially in elderly patients. Bronchospasm (A) is not a common side effect of terazosin. Heart failure (C) is not a typical side effect and is unlikely with proper monitoring. Sedation (D) is not a significant side effect of terazosin.

Correct Answer: D

Rationale: The correct answer is D: Stimulate muscarinic receptors. Parasympathomimetic drugs mimic the actions of the parasympathetic nervous system, which primarily uses acetylcholine on muscarinic receptors to produce its effects. By stimulating muscarinic receptors, these drugs enhance parasympathetic activity. A, B, and C are incorrect: A: Inhibiting muscarinic receptors would have the opposite effect of parasympathomimetic drugs. B: Inhibiting the release of acetylcholine would also reduce parasympathetic activity. C: Inhibiting adrenergic receptors pertains to the sympathetic nervous system, not the parasympathetic system targeted by parasympathomimetic drugs.

Correct Answer: B

Rationale: The correct answer is B: Trimetaphan. Nicotinic receptors are blocked by non-depolarizing neuromuscular blockers like Trimetaphan. Propranolol (A) is a beta-blocker, Prazosin (C) is an alpha-1 blocker, and Pilocarpine (D) is a muscarinic agonist, none of which block nicotinic receptors. Therefore, Trimetaphan (B) is the only choice that directly blocks nicotinic receptors.

Correct Answer: D

Rationale: Selective beta2 stimulants typically cause skeletal muscle tremors due to their action on beta2 receptors in skeletal muscles. They can also lead to tolerance with prolonged use, requiring higher doses for the same effect. Additionally, they can cause tachycardia by stimulating beta2 receptors in the heart. Therefore, all of the above choices (A, B, and C) are correct.

Correct Answer: D

Rationale: The correct answer is D, Edrophonium. Edrophonium is a short-acting cholinesterase inhibitor used in the diagnosis of myasthenia gravis. It does not possess muscarinic blocking activity, as its mechanism of action involves inhibition of acetylcholinesterase leading to increased acetylcholine levels at the neuromuscular junction. The other choices, Amitriptyline (A) is a tricyclic antidepressant with anticholinergic properties, Meperidine (B) has weak antimuscarinic effects, and Ipratropium (C) is an anticholinergic medication used in respiratory conditions. These choices exhibit muscarinic blocking activity, unlike Edrophonium.