Which of the following vitamins reduces the beneficial effects of levodopa by enhancing its extracerebral metabolism?

Correct Answer: A

Rationale: The correct answer is A: Pyridoxine. Pyridoxine (Vitamin B6) accelerates the metabolism of levodopa outside the brain, reducing its effectiveness. This leads to decreased levodopa levels in the brain, diminishing its beneficial effects in treating Parkinson's disease. Thiamine (B1), Tocopherol (E), and Riboflavin (B2) do not have this effect on levodopa metabolism.

Correct Answer: D

Rationale: Step 1: Atypical antipsychotic agents like clozapine have reduced risks of extrapyramidal system dysfunction and tardive dyskinesia compared to typical ones. Step 2: Atypical antipsychotics have low affinity for D1 and D2 dopamine receptors. Step 3: Atypical antipsychotics have high affinity for D4 dopamine receptors. Therefore, the correct answer is D because all the statements are true for atypical antipsychotic agents like clozapine. Other choices are incorrect because they do not cover all the key differences between atypical and typical antipsychotic agents.

Correct Answer: B

Rationale: The correct answer is B: Fluoxetine. Fluoxetine is a Selective Serotonin Reuptake Inhibitor (SSRI) with minimal autonomic toxicity compared to tricyclic antidepressants like Amitriptyline (A), Imipramine (C), and Doxepin (D). SSRIs have a more favorable side effect profile with reduced risk of anticholinergic effects, orthostatic hypotension, and cardiac toxicity. Fluoxetine specifically has a lower affinity for muscarinic, histaminic, and alpha-adrenergic receptors, reducing autonomic side effects. Amitriptyline, Imipramine, and Doxepin are tricyclic antidepressants that have stronger anticholinergic and sedative effects, leading to more autonomic toxicity.

Correct Answer: A

Rationale: Anxiolytics are medications used to treat anxiety disorders, which fall under the category of neurosis. Neurosis is characterized by excessive worry, fear, and distress. Anxiolytics help alleviate symptoms such as restlessness and tension associated with anxiety. Psychosis (choice B) involves loss of touch with reality, narcolepsy (choice C) is a sleep disorder, and bipolar disorders (choice D) involve mood swings between mania and depression. Anxiolytics are not typically indicated for these conditions.

Correct Answer: B

Rationale: The correct answer is B: LSD. Hallucinogens are a class of drugs that alter perception, thoughts, and feelings. LSD, also known as acid, is a well-known hallucinogen that causes visual and auditory hallucinations. Heroin (A) is an opioid, Cocaine (C) is a stimulant, and Opium (D) is an opioid, none of which belong to the hallucinogen category. Therefore, B is the correct answer as it is the only drug related to hallucinogens among the choices provided.