triamterene
Brand: Dyrenium
Prototype: spironolactone
Drug Class: potassium-sparing diuretic
Drug Family: diuretic
Subclass: pteridine-derivative ENaC blocker
Organ Systems: renalcardiovascular
Mechanism of Action
Directly blocks ENaC in the collecting duct reducing sodium reabsorption without requiring aldosterone binding; mild diuresis, K+ sparing.
epithelial sodium channel (ENaC) in collecting duct
Indications
- edema
- hypokalemia prevention (combination with thiazides)
Contraindications
- hyperkalemia
- severe renal impairment
- liver disease
Adverse Effects
Common
- hyperkalemia
- crystalluria (triamterene stones)
- nausea
- GI upset
Serious
- severe hyperkalemia
- renal stones (triamterene)
- megaloblastic anemia (folate antagonism)
Pharmacokinetics (ADME)
| Absorption | 30-70% oral (variable) |
| Distribution | moderate |
| Metabolism | hepatic |
| Excretion | renal |
| Half-life | 1.5-2.5 hours |
| Onset | 2-3 hours |
| Peak | 6 hours |
| Duration | 12-16 hours |
| Protein Binding | 67% |
| Vd | moderate |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| ACE inhibitors/ARBs | additive hyperkalemia | major |
| NSAIDs | AKI risk (especially indomethacin) | major |
| cimetidine | inhibits renal secretion of triamterene — increases levels | moderate |
Nursing Considerations
- Monitor K+ and renal function
- Triamterene can crystallize in urine — maintain hydration
- Often combined with HCTZ (Dyazide, Maxzide) to prevent hypokalemia
- Folate antagonist — megaloblastic anemia in folate-deficient patients
Clinical Pearls
- ENaC blocker: potassium-sparing without aldosterone antagonism — works when spironolactone does not
- Triamterene kidney stones: unique among diuretics
- Weak diuretic alone — used primarily for K+ protection
Safety Profile
Pregnancy avoid
Lactation avoid
Renal Adjustment Required
Hepatic Adjustment Not required
TDM Not required
Concordance Terms
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