A 62-year-old man complained to his physician of facial grimacing, lip smacking, and rocking of the trunk that occurred 1 to 2 hours after taking his prescribed medication. The man, who suffered from Parkinson disease, had been receiving an antiparkinson drug for 3 years. Which of the following drugs most likely caused the adverse effects reported by the patient?

Correct Answer: B

Rationale: The correct answer is B: Levodopa. Levodopa is a common medication used to treat Parkinson's disease. The symptoms described by the patient, such as facial grimacing, lip smacking, and rocking of the trunk, are characteristic of levodopa-induced dyskinesias, which can occur as a side effect of long-term levodopa therapy. Levodopa-induced dyskinesias usually develop after 1-2 hours of taking the medication, as seen in this case. Choice A: Selegiline is a selective MAO-B inhibitor and is less likely to cause the described adverse effects compared to levodopa. Choice C: Entacapone is a catechol-O-methyltransferase (COMT) inhibitor used in combination with levodopa, but it is not known to cause the specific dyskinesias described. Choice D: Amantadine is an antiviral agent with antiparkinsonian effects, but it is

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.

Correct Answer: B

Rationale: The correct answer is B: 5-HT serotonergic receptors. This is because drugs that affect serotonin receptors can cause adverse effects such as serotonin syndrome, which presents with symptoms like confusion, agitation, and hyperthermia. Beta-1 adrenergic receptors (A) are involved in heart function, not typically associated with adverse effects. M cholinergic receptors (C) mediate the parasympathetic nervous system and are unlikely to cause adverse effects in this scenario. Alpha-1 adrenergic receptors (D) are involved in vasoconstriction and blood pressure regulation, not commonly linked to adverse drug effects in this context.