Parasympathomimetic drugs are drugs that:

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: 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.

Correct Answer: A

Rationale: The correct answer is A: Stimulation of beta adrenergic receptors. Propranolol is a beta-blocker that works by blocking beta adrenergic receptors, not stimulating them. Blocking these receptors leads to decreased heart rate, reduced cardiac contractility, and lowered blood pressure. Choices B, C, and D are incorrect because propranolol actually blocks beta adrenergic receptors, depresses cardiac contractility, and decreases blood pressure, respectively.

Correct Answer: D

Rationale: The correct answer is D because catecholamines are structurally similar to adrenaline and noradrenaline, sharing a catechol nucleus and amine group. This similarity allows them to exert similar pharmacologic effects such as increasing heart rate and blood pressure. Adrenergic receptor blockers (A) inhibit the action of catecholamines, atropine-like drugs (B) block muscarinic receptors, and neostigmine and physostigmine (C) are cholinesterase inhibitors, not catecholamines.