Triamterene
DYRENIUM
Pronunciation: trye-AM-ter-een
“Die renally by Trampoline”
Bananas in bunches → ↑ serum potassium
Frightened kidneys → potential for nephrotoxicity
What it isEpithelial sodium-channel blocker in the collecting duct; edema, usually treated alongside a thiazide.
Why this oneDirect ENaC blockade avoids spironolactone's hormonal effects, but its modest diuresis usually makes it a thiazide partner.
What limits itHyperkalemia is the central hazard, especially with an ACE inhibitor or ARB; it can also form kidney stones.
Triamterene prescription history
Animated chart of estimated U.S. prescriptions per year, Diuretics (1953–2026). Triamterene enters in 1964 (estimated).
FDA-approved for
- edema (K-sparing) (~1964)
Principal riskHyperkalemia
Classes and tags
Clinical profile
Legacy pregnancy categoryC
Defining liabilityHyperkalemia and kidney dysfunction, especially with RAAS blockers or impaired renal function.
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Edema (CHF, hepatic cirrhosis, nephrotic syndrome; steroid-induced, idiopathic, secondary hyperaldosteronism) | Adults | 100 mg BID after meals (when used alone) | Titrate to individual response | 300 mg/day |
Renal Contraindicated in anuria and in severe or progressive kidney disease or dysfunction (possible exception: nephrosis)
Hepatic Contraindicated in severe hepatic disease; observe cirrhotics for exacerbation of underlying liver disease
Instructions
- Take after meals to reduce stomach upset; if QD, prefer morning dosing
- Discontinue all potassium supplementation when adding to or switching from other diuretics
- When combined with another diuretic or antihypertensive, lower the initial daily dose of each agent, then adjust
- Monitor serum potassium frequently (especially renal impairment, diabetes, elderly, severely ill); periodic BUN, creatinine and blood counts
Available strengths
- cap 50, 100 mg
Contraindications
- Anuria
- Severe or progressive kidney disease or dysfunction (possible exception: nephrosis)
- Severe hepatic disease
- Pre-existing elevated serum potassium, or hyperkalemia developing on the drug
- Dietary potassium supplements, potassium salts, or potassium-containing salt substitutes
- Other potassium-sparing agents (spironolactone, amiloride, other triamterene-containing formulations) — deaths reported with concomitant spironolactone
Cautions
- Hyperkalemia (K+ >=5.5 mEq/L) can occur and may be fatal if uncorrected — monitor potassium frequently; obtain ECG if hyperkalemia suspected
- Highest hyperkalemia risk: renal impairment, diabetes (even without renal impairment), elderly, severely ill
- Idiosyncratic blood dyscrasias and liver damage — observe regularly
- Electrolyte imbalance in CHF, renal disease, cirrhosis; possible metabolic acidosis; mild reversible nitrogen retention
- Weak folic acid antagonist — megaloblastosis risk with depleted folate stores (e.g., cirrhotics); periodic blood studies
- Elevates uric acid (gout predisposition); caution with history of renal stones (triamterene found in stones)
Adverse reactions
- Hyperkalemia
- Hypokalemia
- Azotemia / elevated BUN and creatinine
- Renal stones
- Acute interstitial nephritis (rare)
- Acute renal failure (one irreversible case)
- Jaundice / liver enzyme abnormalities
- Nausea/vomiting
- Diarrhea
- Thrombocytopenia
- Megaloblastic anemia
- Weakness/fatigue
- Dizziness
- Headache
- Dry mouth
- Anaphylaxis
- Rash
- Photosensitivity
Pregnancy No fetal harm in rat studies up to 20x MRHD; crosses placenta into cord blood; use only if clearly needed — routine diuretic use in healthy pregnant women is inappropriate
Lactation Undefined
Cost
Generic entry2019
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Self-check
- Which collecting-duct channel does triamterene block?
ENaC. - Which antihypertensive classes increase its hyperkalemia concern?
ACE inhibitors and ARBs.