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triamterene (Dyrenium)

Tradename: Dyrenium. Indications: - management of edema & hypertension - hypokalemia [3] Contraindications: - renal insufficiency, avoid eGFR < 30 mL/min Dosage: - 100 mg PO BID; max 300 mg/day Tabs: 50, 100 mg. Pharmacokinetics: 1) full therapeutic effects may not be seen for several days 2) absorption is variable depending upon formulation 3) drug undergoes extensive 1st pass metabolism to an active metabolite 4) 50-55% bound to plasma proteins 5) congugate is 91% bound to plasma proteins 6) both parent & conjugate are filtered & secreted renally 7) elimination 1/2life is 4.1 hours & 3.1 hours for conjugate 8) 1/2life is prolonged in the elderly & in patients with cirrhosis Adverse effects: 1) hyperkalemia, especially in patients with renal failure 2) nausea/vomiting 3) diarrhea 4) increase in blood urea nitrogen (BUN) 5) metabolic acidosis (rare) 6) megaloblastic anemia (rare) Drug interactions: 1) hyperkalemia potentiated by concomitant use of ACE inhibitors, NSAIDs, diabetes 2) NSAIDs can cause adverse effects of renal function & decrease diuretic effect Laboratory: - triamterene in blood - triamterene in serum/plasma - triamterene in urine - triamterene crystals in stone Mechanism of action: 1) K+ sparing diuretic 2) acts directly on distal renal tubule & collecting duct to inhibit reabsorption of Na+ 3) Na+, Cl-, Ca+2, & possibly HCO3- is increased 4) K+ & possibly Mg+2 excretion is decreased

Interactions

drug interactions drug adverse effects (more general classes) monitor with potassium-sparing diuretics

General

K+ sparing diuretic

Properties

MISC-INFO: elimination route LIVER KIDNEY pregnancy-category B safety in lactation -

Database Correlations

PUBCHEM cid=5546

References

  1. The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996
  2. Drug Information & Medication Formulary, Veterans Affairs, Central California Health Care System, 1st ed., Ravnan et al eds, 1998
  3. Deprecated Reference

Component-of

hydrochlorothiazide/triamterene; HCTZ/triamterene (Dyazide, Maxzide, Maxide)