Stimulation of liver microsomal enzymes can:

Correct Answer: A

Rationale: The correct answer is A because stimulation of liver microsomal enzymes can increase drug metabolism, leading to decreased drug levels in the body and requiring a dose increase to maintain therapeutic effect. This is known as enzyme induction. Choices B, C, and D are incorrect because liver enzyme stimulation does not typically result in a decreased drug dose, prolonged drug action, or intensified unwanted drug reactions. It is crucial to understand how enzyme induction affects drug metabolism to optimize drug therapy.

Correct Answer: B

Rationale: Step-by-step rationale: 1. Acetylcholine is the primary neurotransmitter at sympathetic ganglia, parasympathetic ganglia, and parasympathetic postganglionic nerve endings. 2. However, at sympathetic postganglionic nerve endings, norepinephrine is the primary neurotransmitter. 3. Therefore, the correct answer is B because acetylcholine is not the specific neurotransmitter at sympathetic postganglionic nerve endings. Summary: A, C, and D are incorrect because acetylcholine is indeed the specific neurotransmitter at those locations.

Correct Answer: C

Rationale: The correct answer is C: Pirenzepine. Pirenzepine is a selective M1 blocker because it specifically targets the M1 subtype of muscarinic receptors. This selectivity reduces the likelihood of off-target effects associated with non-selective antimuscarinic drugs. Atropine (choice A) and Scopolamine (choice B) are non-selective antimuscarinic drugs, affecting multiple muscarinic receptor subtypes. Homatropine (choice D) is a non-selective antimuscarinic drug primarily used for its mydriatic effect in ophthalmology. Therefore, the correct choice is C as it is the only drug that selectively blocks the M1 receptor subtype.

Correct Answer: C

Rationale: The correct answer is C: Beta1 receptor. Stimulation of Beta1 receptors in the heart leads to increased heart rate, contractility, and conduction velocity. This is crucial for the direct effects on the heart. Alpha1 receptors (choice A) primarily cause vasoconstriction, not direct effects on the heart. Alpha2 receptors (choice B) inhibit norepinephrine release and have minimal effects on the heart. Beta2 receptors (choice D) are mainly found in the lungs and blood vessels, leading to bronchodilation and vasodilation, rather than direct effects on the heart.

Correct Answer: A

Rationale: The correct answer is A: Drug-induced parkinsonism. Sympathomimetics stimulate the sympathetic nervous system, which can lead to adverse effects like cerebral hemorrhage, pulmonary edema, myocardial infarction, and ventricular arrhythmias due to increased heart rate and blood pressure. However, they do not cause drug-induced parkinsonism, which is associated with medications that affect dopamine levels in the brain. Therefore, choice A is the correct answer. Choices B, C, and D are incorrect because sympathomimetics can indeed lead to these adverse effects due to their actions on the sympathetic nervous system.