Tick the antimycobacterial drug belonging to second-line agents:

Correct Answer: B

Rationale: The correct answer is B: PAS (para-aminosalicylic acid) because it is a second-line antimycobacterial drug used to treat drug-resistant tuberculosis. Isoniazid and rifampin are first-line agents, and streptomycin is an aminoglycoside antibiotic primarily used for treating bacterial infections, not specifically for mycobacterial infections. PAS is specifically indicated for multidrug-resistant tuberculosis cases, making it a second-line option.

Correct Answer: D

Rationale: The correct answer is D: Anastrozole. Anastrozole is an aromatase inhibitor that works by blocking the enzyme aromatase, which is responsible for converting androgens into estrogen. By inhibiting estrogen production, Anastrozole effectively reduces estrogen levels in the body. Leuprolide (A) is a gonadotropin-releasing hormone agonist that suppresses estrogen production indirectly. Tamoxifen (B) is a selective estrogen receptor modulator that blocks estrogen receptors. Flutamide (C) is an antiandrogen that blocks the effects of androgens, not estrogen.

Correct Answer: A

Rationale: The correct answer is A: Lovastatin. Lovastatin is a statin medication that can increase the risk of bleeding, which would be problematic for a patient with hemophilia and external hemorrhoids. Statins can interfere with the liver's production of clotting factors, exacerbating bleeding issues in hemophiliac patients. Choice B: Cholestyramine is a bile acid sequestrant used to lower cholesterol levels and is not directly contraindicated in hemophilia or hemorrhoids. Choice C: Ezetimibe is a cholesterol absorption inhibitor and does not directly affect bleeding risk in hemophiliac patients with hemorrhoids. Choice D: Niacin is a B vitamin that can cause flushing and itching, but it does not have a direct contraindication in patients with hemophilia and external hemorrhoids.

Correct Answer: C

Rationale: The correct answer is C because cholestyramine can bind to propranolol in the gut, preventing its absorption and leading to an increase in oral bioavailability. This occurs due to the cholestyramine-propranolol complex being excreted in the feces, reducing the amount of propranolol available for systemic circulation. Choice A is incorrect because propranolol clearance would decrease, not increase, as less drug is absorbed and more is excreted in the feces. Choice B is incorrect as cholestyramine does not directly affect the clearance of hydrochlorothiazide. Choice D is incorrect as there is a clear pharmacokinetic interaction between cholestyramine and propranolol.

Correct Answer: B

Rationale: In treating a patient with congestive heart failure (CHF), selecting the appropriate dosage of dopamine is crucial for its positive inotropic effects. The correct dosage in this scenario is option B) 5-10 mg/kg/min. This dosage range is selected because dopamine acts on specific receptors in the heart that increase contractility, thereby improving cardiac output in CHF. Option A) 2.0 mg/kg/min is too low to produce the desired positive inotropic effects in CHF patients. Option C) 10-20 mg/kg/min is a higher dosage range that may lead to excessive vasoconstriction and increased afterload, potentially worsening the patient's condition. Option D) 40 mg/kg/min is an extremely high dosage that can cause severe vasoconstriction, leading to decreased coronary perfusion and worsening of CHF symptoms. Educationally, understanding the rationale behind selecting the appropriate dosage of dopamine in CHF patients is essential for healthcare professionals involved in managing cardiovascular diseases. It emphasizes the importance of dosing precision to achieve therapeutic effects while minimizing adverse outcomes. By grasping the pharmacological principles behind dopamine's effects on the cardiovascular system, clinicians can make informed decisions tailored to each patient's specific condition, ultimately improving patient outcomes.