A heart failure patient has unreliable response to oral furosemide despite dose escalation, with wide day-to-day variation in diuresis. Switching to which agent best addresses the pharmacokinetic problem responsible?

• A Bumetanide, which has more consistent and complete oral absorption ✓
• B Hydrochlorothiazide, which has near complete bioavailability
• C Acetazolamide, which is always fully absorbed orally
• D Spironolactone, whose absorption is unaffected by gut edema

Explanation

Oral furosemide bioavailability is highly variable, roughly 10 to 100 percent between patients, and gut mucosal edema in heart failure further delays and reduces absorption, explaining erratic responses. Bumetanide and torsemide have consistently high oral bioavailability of around 80 percent or more, giving predictable absorption. Hydrochlorothiazide is well absorbed but ineffective at low GFR and far weaker than a loop agent in significant heart failure.

Reference: Katzung Basic and Clinical Pharmacology, 15th ed.

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Written and medically reviewed by the StethoPrep medical team.