In contrast to morphine heroin is:

Correct Answer: B

Rationale: The correct answer is B: More addictive and fast-acting. Heroin is derived from morphine and is more potent, leading to a faster onset of action and increased addictive potential. The rapid crossing of the blood-brain barrier contributes to its fast-acting properties. It is crucial to differentiate between heroin and morphine due to their varying addictive nature and speed of action. Choices A, C, and D are incorrect because heroin is not typically used clinically, is not more effective orally, and is actually more potent and faster-acting than morphine, making it not less potent and long-acting.

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.

Correct Answer: D

Rationale: The correct answer is D because the main principle of shock treatment is to improve peripheral blood flow to vital organs and tissues. By improving peripheral blood flow, oxygen and nutrients can reach affected areas, helping to restore cellular function. Increasing arterial pressure (A) may worsen tissue perfusion, increasing peripheral vascular resistance (B) can further impair blood flow, and increasing cardiac output (C) may not address the underlying issue of poor peripheral blood flow in shock conditions.