Warfarin:

Correct Answer: C

Rationale: Warfarin is highly bioavailable (near 100%), so 90% is close and true. It doesn't inactivate vitamin K but inhibits vitamin K epoxide reductase, reducing clotting factor synthesis, making that false. It can paradoxically cause venous thrombosis (e.g., skin necrosis) early in therapy due to protein C depletion, a true statement. Initial loading is typically 5-10 mg, not 0.5 mg, so that's false. Metronidazole increases its effect via metabolism inhibition, not bactericidal action. The thrombosis risk is a rare but serious side effect, highlighting the need for bridging with heparin during initiation.

Correct Answer: A

Rationale: A common side effect of Albuterol, a bronchodilator medication used to treat asthma and other respiratory conditions, is paradoxical bronchospasm. This paradoxical reaction leads to an unexpected constriction of the airways instead of the expected relaxation. It can result in increased breathing difficulties and chest tightness, requiring immediate medical attention. Other possible side effects of Albuterol include tremors, palpitations, headache, and nervousness, but paradoxical bronchospasm is notable due to its potential severity and the need for prompt intervention.

Correct Answer: B

Rationale: Finasteride (Proscar), a 5-alpha reductase inhibitor, reduces prostate size in benign prostatic hyperplasia (BPH) by blocking dihydrotestosterone (DHT) production, shrinking glandular tissue and easing urinary obstruction. Relaxing penile smooth muscle is the role of phosphodiesterase-5 inhibitors like sildenafil, not finasteride. It lowers DHT, not testosterone, and may even slightly increase circulating testosterone, but that's not its aim. Stimulating RNA synthesis relates to androgens' anabolic effects, not finasteride's mechanism. Shrinking the prostate is its core function, taking months to reduce symptoms, distinct from acute smooth muscle relaxation or hormonal boosts, aligning with BPH management goals.

Correct Answer: C

Rationale: Warfarin is highly bioavailable (near 100%), so 90% is close and true. It doesn't inactivate vitamin K but inhibits vitamin K epoxide reductase, reducing clotting factor synthesis, making that false. It can paradoxically cause venous thrombosis (e.g., skin necrosis) early in therapy due to protein C depletion, a true statement. Initial loading is typically 5-10 mg, not 0.5 mg, so that's false. Metronidazole increases its effect via metabolism inhibition, not bactericidal action. The thrombosis risk is a rare but serious side effect, highlighting the need for bridging with heparin during initiation.

Correct Answer: D

Rationale: Actifed Plus combines acetaminophen (an analgesic) with antihistamine and decongestant, relieving pain alongside allergy symptoms. Sudafed PE and Triaminic contain chlorpheniramine and phenylephrine, no analgesics. Tavist has clemastine alone. Choice D's analgesic property distinguishes it, relevant for nurses advising on OTC options.