Dosing & Uses
Dosage Forms & Strengths
capsule
- 50mg
- 100mg
Edema
100-300 mg/day PO qDay or divided q12hr
Hypertension (Off-label)
50-100 mg PO qDay or divided q12hr
Renal Impairment
CrCl <10 mL: Do not use
Hepatic Impairment
Reduce dose in patients with cirrhosis
Other Information
Monitor serum potassium
See also combo with HCTZ
Dosage Forms & Strengths
capsule
- 50mg
- 100mg
Hypertension (Off-label)
Safety & efficacy not established
1-2 mg/kg/day PO divided q12hr
Maximum dose: 3-4 mg/kg/day PO divided q12hr up to 300 mg/day
Consider lower initial doses
Edema
50-300 mg/day PO qDay or divided q12hr
Hypertension
50-300 mg/day PO qDay or divided q12hr
Interactions
Interaction Checker
No Results

Contraindicated
Serious - Use Alternative
Significant - Monitor Closely
Minor

Adverse Effects
1-10%
CHF
Edema
Hypotension
Dizziness
Fatigue
HA
Photosensitivity
Rash
Diarrhea
Nausea
Vomiting
Hyperuricemia
Nephrotoxicity
Frequency Not Defined
GI upset
Thrombocytopenia
Nephrolithiasis
Folic acid antagonism
Warnings
Contraindications
Hypersensitivity to triamterene
Anuria, severe liver disease, renal failure
Hyperkalemia
Concomitant use with K+-sparing diuretic, or K supplementation
Cautions
Use caution in acid-base imbalance, electrolyte abnormalities, hyperuricemia or gout, liver disease, renal impairment, renal stones
Patients should be observed regularly for possible occurrence of blood dyscrasias, liver damage or other idiosyncratic reactions
Periodic BUN and serum potassium determinations should be made to check kidney function, especially in patients with suspected or confirmed renal insufficiency; particularly important to make serum potassium determinations in elderly or diabetic patients receiving drug; these patients should be observed carefully for possible serum potassium increases
Electrolyte imbalance often encountered in diseases such as congestive heart failure, renal disease or cirrhosis may be aggravated or caused independently by any effective diuretic agent including triamterene; use of full doses of a diuretic when salt intake is restricted can result in a low-salt syndrome
Triamterene can cause mild nitrogen retention, which is reversible upon withdrawal of drug and is seldom observed with intermittent (every-other-day) therapy
Therapy may cause a decreasing alkali reserve, with possibility of metabolic acidosis
By the very nature of their illness, cirrhotics with splenomegaly sometimes have marked variations in their blood; since triamterene is a weak folic acid antagonist, it may contribute to appearance of megaloblastosis in cases where folic acid stores have been depleted; periodic blood studies in these patients recommended; observe also for exacerbations of underlying liver disease
Triamterene has elevated uric acid, especially in persons predisposed to gouty arthritis
Triamterene reported in renal stones in association with other calculus components; drug should be used with caution in patients with histories of renal stones
Interferes with fluorescent assay of quinidine
Not recommended for pregnancy-induced HTN; use during pregnancy may increase risk of cardiovascular defects and oral cleft in child
Hyperkalemia
- Drug tends to conserve potassium rather than to promote excretion as do many diuretics and, occasionally, can cause increases in serum potassium which, in some instances, can result in hyperkalemia; in rare instances, hyperkalemia has been associated with cardiac irregularities
- If hyperkalemia present or suspected, obtain an electrocardiogram; if tECG shows no widening of QRS or arrhythmia in presence of hyperkalemia, it is usually sufficient to discontinue therapy and any potassium supplementation, and substitute a thiazide alone
- Sodium polystyrene sulfonate may be administered to enhance excretion of excess potassium; presence of a widened QRS complex or arrhythmia in association with hyperkalemia requires prompt additional therapy
- For tachyarrhythmia, infuse 44 mEq of sodium bicarbonate or 10 mL of 10% calcium gluconate or calcium chloride over several minutes; for asystole, bradycardia or A-V block transvenous pacing is also recommended
- Effect of calcium and sodium bicarbonate is transient and repeated administration may be required; when indicated by clinical situation, excess K+ may be removed by dialysis or oral or rectal administration of Kayexalate®. Infusion of glucose and insulin has also been used to treat hyperkalemia
Pregnancy & Lactation
Pregnancy Category: C
Lactation: Discontinue drug or nursing
Pregnancy Categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk. C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done. D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk. X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist. NA: Information not available.Pharmacology
Mechanism of Action
Direct effect on renal distal tubule to inhibit Na+ reabsorption
Inhibits Na/K-ATPase, decreases Ca++ , Mg++ and hydrogen excretion
Pharmacokinetics
Half-Life: 1.5-2.5 hr
Duration: 7-9 hr
Onset: Initial effect: 2-4 hr; Max effect: diuresis: several days, HTN: 2-3 months
Peak Plasma Time: 1.5-3 hr
Bioavailability: 30-70%
Protein Bound: 55-67%
Metabolism: Liver
Metabolites: hydroxytriamterene sulfate (active)
Excretion: urine 21%
Dialyzable: Yes (hemodialysis)
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Formulary
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