Which antiepileptic drug would be most appropriate for the 54-year-old man with complex partial seizure, atrioventricular block, and nephrolithiasis?

Correct Answer: A

Rationale: The correct answer is A: Carbamazepine. It is the most appropriate choice due to its efficacy in treating complex partial seizures. Carbamazepine is also less likely to worsen atrioventricular block compared to other antiepileptic drugs. Furthermore, it does not typically exacerbate nephrolithiasis. Phenytoin (B) can worsen atrioventricular block and does not specifically target complex partial seizures. Valproic acid (C) is contraindicated in patients with nephrolithiasis. Ethosuximide (D) is primarily used for absence seizures, not complex partial seizures.

Correct Answer: B

Rationale: The correct answer is B: Decreased acetylcholine release from cholinergic terminals. Acetylcholine release from cholinergic terminals contributes to the parasympathetic response, which can cause adverse effects such as bradycardia. By decreasing acetylcholine release, the parasympathetic response is reduced, leading to a more balanced autonomic control of the heart rate. Activation of cardiac dopamine receptors (choice A) and β receptors (choice C) would usually have positive effects on the heart, while blockade of cardiac M receptors (choice D) would exacerbate the adverse effects by blocking the already decreased parasympathetic response.

Correct Answer: D

Rationale: The correct answer is D: Clozapine. Clozapine is the most appropriate choice for a 29-year-old man with chronic paranoid schizophrenia at this stage due to its efficacy in treatment-resistant cases and lower risk of extrapyramidal side effects. It is often considered a last resort due to its potential side effects, such as agranulocytosis, which requires regular monitoring. A: Fluphenazine and B: Thioridazine are typical antipsychotics with a higher risk of extrapyramidal side effects and are less effective in treatment-resistant cases compared to Clozapine. C: Fluoxetine is an antidepressant and not typically used as a first-line treatment for schizophrenia. It is more commonly used for depressive symptoms that may co-occur with schizophrenia.

Correct Answer: C

Rationale: The correct answer is C: Haloperidol. The patient's syndrome is most likely caused by Haloperidol, an antipsychotic drug known to cause extrapyramidal symptoms such as dystonia, akathisia, and parkinsonism. Imipramine (A) is a tricyclic antidepressant associated with anticholinergic effects. Temazepam (B) is a benzodiazepine used for insomnia. Fluoxetine (D) is a selective serotonin reuptake inhibitor used for depression and not typically associated with extrapyramidal symptoms. Therefore, the most likely culprit is Haloperidol due to its known side effect profile.

Correct Answer: C

Rationale: Rationale: The correct answer is C because increased expression of brain-derived neurotrophic factor (BDNF) is a common mechanism underlying the therapeutic effectiveness of long-term therapy with most antidepressants. BDNF promotes neuronal survival, growth, and differentiation, which are essential for mood regulation and combating depression. A: Inhibition of central monoamine metabolism is a common mechanism of action for some antidepressants, but not all. B: Upregulation of central postsynaptic adrenoceptors is not a common mechanism of action for antidepressants. D: Decreased hippocampal neurogenesis is associated with depression, and antidepressants aim to increase neurogenesis.