Which dosage of benzodiazepines for 60-90 days may produce severe withdrawal symptoms?

Correct Answer: C

Rationale: The correct answer is C: More than 800 mg/d. High doses of benzodiazepines increase the risk of developing physical dependence, leading to severe withdrawal symptoms when discontinued. Dosages exceeding 800 mg/d are considered very high and are more likely to result in severe withdrawal symptoms after prolonged use. Choices A, B, and D all suggest lower dosages which are less likely to cause severe withdrawal symptoms compared to doses exceeding 800 mg/d. Therefore, option C is the correct choice for the dosage of benzodiazepines that may produce severe withdrawal symptoms after 60-90 days of use.

Correct Answer: A

Rationale: The correct answer is A: Sodium bicarbonate. Sodium bicarbonate causes metabolic alkalosis by increasing bicarbonate levels in the body, leading to an excess of base. This can occur in conditions like overdose or prolonged use. B: Cimetidine is an H2 receptor antagonist that can cause metabolic acidosis, not alkalosis. C: Pepto-Bismol contains bismuth subsalicylate and can cause metabolic acidosis. D: Carbenoxolone is a drug that can cause metabolic alkalosis.

Correct Answer: B

Rationale: The correct answer is B: FALSE. Urokinase is a thrombolytic agent that activates plasminogen to plasmin, which dissolves blood clots. It does not inhibit Thromboxane A2. Thromboxane A2 is involved in platelet aggregation and vasoconstriction. Choices A, C, and D are incorrect because urokinase does not inhibit Thromboxane A2.

Correct Answer: A

Rationale: Verapamil is a calcium channel blocker that slows the influx of calcium ions in cardiac cells, leading to a decrease in automaticity in the SA node. This results in a decrease in heart rate. Therefore, choice A is correct. Choice B is incorrect because verapamil does affect automaticity. Choices C and D are incorrect as they do not accurately reflect the specific effect of verapamil on automaticity in the SA node.

Correct Answer: B

Rationale: Verapamil is a calcium channel blocker that slows down the heart rate by blocking L-type calcium channels. This action helps in reducing blood pressure and controlling heart rhythm. Therefore, statement B stating that verapamil increases heart rate is incorrect. Choices A, C, and D are true as verapamil blocks L-type calcium channels, relaxes coronary artery smooth muscle, and depresses cardiac contractility, respectively.