Generic Name

Torsemide

Mechanism

• Loop diuretic: competitively blocks the Na⁺‑K⁺‑2Cl⁻ symporter (NKCC2) on the luminal membrane of the thick ascending limb, preventing reabsorption of sodium, potassium, and chloride.
• Resulting osmotic diuresis increases urine volume and excretion of electrolytes.
• Inhibits calcium reabsorption, leading to calciuria.
• Provides a more sustained diuresis than furosemide due to longer plasma half‑life and better oral bioavailability.

Pharmacokinetics

• Absorption: >80 % oral bioavailability; peak plasma levels reached in 1–2 h.
• Distribution: ~95 % plasma protein‑bound; crosses the blood‑urine barrier.
• Metabolism: partial hepatic ester hydrolysis (≈40 %) to inactive metabolites.
• Elimination: ~10 % renally unchanged; the remainder excreted renally or via biliary‐associated excretion of metabolites.
• Half‑life: ≈2 h; clinical duration of action ≈6–10 h.
• Drug interactions: potentiates effects of ACE inhibitors, ARBs, and NSAIDs; may potentiate hypokalemia.

Indications

• Congestive heart failure: acute or chronic fluid overload.
• Liver cirrhosis with refractory ascites.
• Nephrotic syndrome with edema.
• Pulmonary edema (as adjunct to other therapies).

Contraindications

• Absolute: anuria, severe electrolyte imbalance, hypersensitivity to sulfonylureas or sulfonamides.
• Caution:
• Renal impairment: dose reduction; monitor GFR.
• Hepatic impairment: dose adjustment; avoid in severe cirrhosis.
• Pregnancy: Category C; avoid unless benefits outweigh risks.
• Breastfeeding: not recommended.
• Warnings:
• Hypotension, dehydration, and renal failure in volume‑depleted patients.
• Hyperuricemia: risk of gout flare.
• Ototoxicity is rare but increased with high doses or rapid IV admin.

Dosing

*For IV administration (rare), 20–40 mg once daily with a 5‑min infusion to mitigate ototoxicity.*

Adverse Effects

• Common
• Dehydration, hypotension
• Electrolyte disturbances: hypokalemia, hyponatremia, hypomagnesemia, hypocalcemia
• Hyperuricemia, gout flare
• Diarrhea, nausea
• Serious
• Acute kidney injury (AKI) from volume depletion
• Severe electrolyte imbalance (e.g., hyperkalemia in renal failure)
• Ototoxicity (rare, especially with rapid IV)
• Hypersensitivity reactions (rash, angioedema)

Monitoring

• Fluid status: daily weights, urine output.
• Serum electrolytes: K⁺, Na⁺, Cl⁻, Mg²⁺, Ca²⁺ (baseline, 48 h, then weekly).
• Renal function: BUN, creatinine, eGFR (baseline, 48 h, then as indicated).
• Hemodynamic: BP, HR.
• Liver enzymes (if hepatic impairment suspected).
• Audiometry: if high‑dose IV or prolonged therapy (>14 days).

Clinical Pearls

• Long‑acting profile: Torsemide’s sustained action (6–10 h) allows once‑daily dosing versus furosemide’s 2–4 h window; this improves adherence in outpatient heart‑failure management.
• Higher oral efficacy in renal impairment: Because of its hepatic metabolism, torsemide retains potency even when renal clearance is reduced, making it a preferred choice in chronic kidney disease patients.
• Avoid rapid IV bolus: A slow 5‑minute infusion mitigates the risk of ototoxicity, a concern especially in patients receiving concomitant aminoglycosides or cisplatin.
• Calcium balance: Monitor serum calcium in patients on calcium‑supplemented diets; torsemide’s calciuric effect may predispose to hypocalcemia.
• Combination with potassium‑sparing agents: The addition of spironolactone or amiloride counteracts torsemide‑induced hypokalemia but may risk hyperkalemia—balance with careful lab monitoring.
• Dietary sodium: Counsel patients to keep sodium intake <2 g/day to maximize diuretic efficacy and reduce rebound edema.

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• With this concise, high‑yield drug card, medical students and clinicians can quickly reference torsemide’s pharmacologic profile, dosing guidelines, safety considerations, and practical tips for optimal patient care.