The acute course of opioid withdrawal may last:

Correct Answer: B

Rationale: The correct answer is B: 7-10 days. Opioid withdrawal symptoms typically start within 6-12 hours after the last dose and peak around 2-3 days. The acute phase, marked by intense symptoms like anxiety, sweating, and insomnia, usually lasts about a week. After this period, symptoms gradually improve. Choices A, C, and D are incorrect. Choice A is too short for the acute phase. Choice C is too long, indicating the more prolonged post-acute withdrawal phase. Choice D is significantly longer and indicative of a chronic condition, not acute withdrawal.

Correct Answer: B

Rationale: The correct answer is B: Cisapride. Cisapride is a prokinetic agent that enhances gastrointestinal motility, therefore it does not reduce intestinal peristalsis. Loperamide (A) is an anti-diarrheal drug that acts by slowing down intestinal peristalsis. Methyl cellulose (C) is a bulk-forming laxative that can help regulate bowel movements by increasing stool bulk and promoting peristalsis. Magnesium aluminium silicate (D) is an antacid that can potentially slow down intestinal transit time by absorbing water in the intestine. So, B is the correct answer as it is the only drug that does not reduce intestinal peristalsis.

Correct Answer: A

Rationale: The correct answer is A: Digoxin. Foxglove (Digitalis) is a plant known for containing cardiac glycosides, specifically digoxin. Digoxin is derived from the leaves of the Foxglove plant and is commonly used to treat heart conditions such as heart failure and atrial fibrillation. Strophantin K is a cardiac glycoside derived from the Strophanthus plant. Dobutamine is a synthetic catecholamine used as a cardiac stimulant. Amrinone is a phosphodiesterase inhibitor used for treating heart failure. These choices are incorrect as they are not derivatives of the plant Foxglove.

Correct Answer: C

Rationale: The correct answer is C: Amyl nitrite, inhalant. Amyl nitrite is a short-acting drug used for the treatment of angina pectoris and cyanide poisoning. It works quickly to dilate blood vessels and relieve chest pain. Nitroglycerin ointment and sustained-release tablets have longer durations of action, making them not short-acting. Sustac is not a nitrate or nitrite drug, so it is an incorrect choice. Overall, the rapid onset and short duration of action of amyl nitrite make it the correct choice for a short-acting nitrate/nitrite drug.

Correct Answer: C

Rationale: The correct answer is C: Phenylephrine. Phenylephrine is a synthetic vasoconstrictor that acts by stimulating adrenergic receptors, specifically alpha-adrenergic receptors, leading to vasoconstriction. Noradrenaline (A) and adrenaline (B) are endogenous catecholamines that also have vasoconstrictive effects but are not synthetic. Angiotensinamide (D) is not a synthetic vasoconstrictor and acts through a different mechanism involving the renin-angiotensin system. In summary, Phenylephrine is the correct choice as it is a synthetic vasoconstrictor with adrenomimetic effects, while the other options do not fit this description.