Most antipsychotic drugs:

Correct Answer: A

Rationale: Step 1: Antipsychotic drugs primarily act by blocking dopamine receptors, especially D2 receptors. Step 2: Blocking D2 receptors reduces dopamine activity, helping control psychotic symptoms. Step 3: Option A is correct as antipsychotics strongly block postsynaptic D2 receptors. Summary: - B is incorrect as stimulating D2 receptors would worsen psychotic symptoms. - C is incorrect as antipsychotics do not typically block NMDA receptors. - D is incorrect as antipsychotics primarily target dopamine receptors, not 5-HT2 receptors.

Correct Answer: D

Rationale: The correct answer is D: Piracetam. Piracetam is a nootropic, which means it enhances cognitive function, memory, and learning. It is not a CNS stimulant like choices A, B, and C. Camphor is a topical analgesic, Pantocrin is an adrenal extract, and Sydnocarb is a stimulant used in treating narcolepsy. Piracetam stands out as a nootropic due to its specific cognitive-enhancing effects, making it the correct choice in this context.

Correct Answer: D

Rationale: The correct answer is D: All of the above. Cocaine, amphetamine, and caffeine are all stimulant drugs that affect the central nervous system, leading to increased alertness, energy, and euphoria. Cocaine is a powerful stimulant derived from the coca plant, amphetamine is a synthetic stimulant commonly used as a prescription medication or illicit drug, and caffeine is a naturally occurring stimulant found in coffee, tea, and other beverages. All three substances have similar effects on the body, making them related to stimulants. Therefore, the correct answer is D as all the options (A, B, and C) are related to stimulants.

Correct Answer: B

Rationale: Step 1: Chymotrypsin is a protease enzyme, not an agent containing free sulfhydryl groups. Step 2: Protease enzymes like chymotrypsin contain amino acids in their active site, not sulfhydryl groups. Step 3: Therefore, the statement that chymotrypsin is an agent containing free sulfhydryl groups is FALSE. Summary: Choice B is correct because chymotrypsin does not contain free sulfhydryl groups. Choices A, C, and D are incorrect because they do not accurately reflect the nature of chymotrypsin.

Correct Answer: C

Rationale: The correct answer is C: Loperamide. Loperamide is an antidiarrheal medication that works by slowing down gut motility and inhibiting peristalsis in the intestines. This helps to increase the absorption of water and electrolytes, leading to firmer stools. Castor oil (A) and Sorbitol (D) are laxatives that promote peristalsis and bowel movements. Bisacodyl (B) is a stimulant laxative that increases intestinal motility and promotes bowel movements. Therefore, choices A, B, and D are incorrect as they have the opposite effect of inhibiting peristalsis.