Caffeine does not cause:

Correct Answer: A

Rationale: The correct answer is A because caffeine actually stimulates gastric secretion, not inhibits it. Caffeine can increase stomach acid production, leading to potential digestive issues. Choices B, C, and D are incorrect because caffeine is known to cause hyperglycemia by increasing blood sugar levels, has a moderate diuretic action by increasing urine production, and increases free fatty acids in the bloodstream, which can affect metabolism. Therefore, based on its effects on gastric secretion, A is the correct answer.

Correct Answer: B

Rationale: Step 1: Ketamine is the correct choice for dissociative anesthesia due to its unique mechanism of action, which involves blocking NMDA receptors, leading to dissociation of sensory input from conscious perception. Step 2: Midazolam (A) is a benzodiazepine used for sedation and anxiolysis, not dissociative anesthesia. Step 3: Fentanyl (C) is an opioid analgesic used for pain control, not dissociative anesthesia. Step 4: Thiopental (D) is a barbiturate used for induction of general anesthesia, not specifically for dissociative anesthesia.

Correct Answer: D

Rationale: The correct answer is D: Apomorphine hydrochloride. Apomorphine hydrochloride is not an antiemetic; it is a dopamine agonist primarily used to treat Parkinson's disease. Metoclopramide, Ondansetron, and Chlorpromazine are all antiemetic drugs that work by different mechanisms to alleviate nausea and vomiting. Metoclopramide acts as a dopamine antagonist and 5-HT3 receptor antagonist, Ondansetron is a selective 5-HT3 receptor antagonist, and Chlorpromazine is a dopamine antagonist with antiemetic properties. Therefore, D is the correct answer as it does not belong to the class of antiemetic drugs.

Correct Answer: D

Rationale: The correct answer is D: All of the above. Sugar molecules in glycosides can affect cardiotonic action by enhancing heart function, impact pharmacokinetic properties by influencing drug absorption and metabolism, and contribute to toxic properties by affecting bioavailability and toxicity. Therefore, all the options (A, B, C) are influenced by sugar molecules in glycosides.

Correct Answer: D

Rationale: The correct answer is D: All of the above. Rationale: A: Therapeutically active nitrates release NO, which activates guanylyl cyclase in vascular smooth muscle, leading to vasodilation. B: Nitric oxide activates soluble guanylyl cyclase, promoting cGMP production, causing vasodilation and reducing blood pressure. C: Nitrates decrease myocardial oxygen demand by reducing preload and afterload, while also increasing oxygen delivery by dilating coronary arteries. Summary: Option A highlights the release of NO, contributing to vasodilation. Option B explains NO's role in activating guanylyl cyclase. Option C describes the dual mechanism of nitrates in decreasing oxygen demand and increasing oxygen delivery. Therefore, the correct answer includes all valid statements regarding nitrate mechanism of action.