Which of the following drugs is an nonselective beta receptor antagonist?

Correct Answer: C

Rationale: Rationale: 1. Propranolol is a nonselective beta receptor antagonist, blocking both beta-1 and beta-2 receptors. 2. Metoprolol and Atenolol are selective beta-1 receptor antagonists. 3. Acebutolol is a partial beta-1 antagonist with intrinsic sympathomimetic activity. 4. Propranolol is used for conditions requiring nonselective beta blockade, like hypertension and angina.

Correct Answer: C

Rationale: Step-by-step rationale: 1. Phenytoin is known to cause gingival hyperplasia. 2. This adverse effect is dose-related, meaning it occurs more frequently with higher doses. 3. Gingival hyperplasia is characterized by overgrowth of gum tissue. 4. It is not associated with physical or psychological dependence, exacerbated seizures, or extrapyramidal symptoms. Summary: Choice A is incorrect as phenytoin does not cause dependence. Choice B is incorrect as phenytoin does not worsen seizures. Choice D is incorrect as extrapyramidal symptoms are not typically caused by phenytoin.

Correct Answer: D

Rationale: Rationale: 1. Carbidopa inhibits the peripheral metabolism of levodopa, leading to increased levodopa blood levels and prolonged half-life. 2. By enhancing levodopa bioavailability, carbidopa allows for a significant reduction in levodopa dose, minimizing toxic effects. 3. Carbidopa also reduces the latency period before beneficial effects occur. Therefore, the correct answer is D, as all statements are true and supported by pharmacological principles. Other choices are incorrect as they do not encompass the comprehensive effects of combining carbidopa and levodopa.

Correct Answer: B

Rationale: The correct answer is B: Coma, depressed respiration, and miosis. In opioid overdosage, coma occurs due to central nervous system depression, depressed respiration is a result of respiratory center suppression, and miosis is a classic sign of opioid toxicity due to the activation of the parasympathetic nervous system. Mydriasis (pupil dilation) is not a common feature in opioid overdosage. Chills and abdominal cramps are more indicative of opioid withdrawal rather than overdose. Tremor and vomiting are not typically part of the diagnostic triad of opioid overdosage.

Correct Answer: A

Rationale: The correct answer is A: The nigrostriatal system. Parkinsonian symptoms and tardive dyskinesia are caused by dopamine blockade in the nigrostriatal system, which is responsible for motor control. Dopamine blockade here leads to movement disorders. Choices B, C, and D are incorrect because tardive dyskinesia and Parkinsonian symptoms are not primarily related to dopamine blockade in the mesolimbic and mesofrontal systems (B), chemoreceptor trigger zone of the medulla (C), or the tuberoinfundibular system (D). These systems are associated with other functions such as reward processing, nausea/vomiting regulation, and hormone release, respectively.