The mechanism of valproate action is:

Correct Answer: D

Rationale: The correct answer is D: All of the above. Valproate's mechanism of action involves multiple pathways. 1. Valproate facilitates GABA synthesis by inhibiting GABA breakdown enzyme and enhancing GABA accumulation. 2. It inhibits voltage-sensitive Na+ channels, reducing neuronal excitability. 3. It also inhibits low threshold (T-type) Ca2+ channels, further reducing neuronal excitability. These combined actions lead to increased GABAergic transmission and decreased excitatory neurotransmission, contributing to its antiepileptic and mood stabilizing effects. Other choices are incorrect because they do not encompass all the mechanisms involved in valproate's action.

Correct Answer: D

Rationale: The correct answer is D: Acetaldehyde. Disulfiram inhibits the enzyme aldehyde dehydrogenase, leading to accumulation of acetaldehyde when alcohol is consumed. Acetaldehyde buildup causes unpleasant symptoms like flushing, nausea, and headache. Formaldehyde (A) is not directly related to this interaction. Acetate (B) is a product of alcohol metabolism, not affected by disulfiram. Formic acid (C) is associated with methanol toxicity, not disulfiram-alcohol reaction. Therefore, the correct answer is D, as it aligns with the mechanism of action of disulfiram.

Correct Answer: C

Rationale: The correct answer is C: Haloperidol. Haloperidol is preferable in patients with coronary and cerebrovascular disease due to its lower risk of causing cardiovascular adverse effects compared to the other options. Chlorpromazine (A) can cause orthostatic hypotension and prolong QT interval. Fluphenazine (B) can lead to QT prolongation and hypotension. Perphenazine (D) also carries a risk of QT prolongation and orthostatic hypotension. In contrast, Haloperidol has a more favorable cardiovascular safety profile, making it the preferred choice for patients with coronary and cerebrovascular disease.

Correct Answer: A

Rationale: The correct answer is A: Meridil. Psychostimulants are substances that can increase alertness, attention, and energy levels. Meridil, also known as methylphenidate, is a commonly prescribed psychostimulant used to treat conditions like ADHD. Camphor (B) is a topical analgesic, Piracetam (C) is a nootropic agent, and Pantocrin (D) is a herbal supplement with purported energy-boosting properties. Therefore, only Meridil (A) fits the classification of a psychostimulant among the choices provided.

Correct Answer: C

Rationale: The correct answer is C: Buspirone. Buspirone is an anxiolytic agent that relieves anxiety without causing marked sedative effects. It works by specifically targeting serotonin receptors in the brain to reduce anxiety, unlike benzodiazepines like Diazepam, Chlordiazepoxide, and Clorazepate which act on GABA receptors leading to sedative effects. Buspirone's unique mechanism of action makes it an ideal choice for treating anxiety without causing sedation.