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Indications and Dosage
Oral
Oedema Adult: As monotherapy: Dose range: 150-250 mg daily in 2 divided doses. For maintenance treatment, doses may be given on alternate days. Max: 300 mg daily. Use lower initial dose when combined with another diuretic, then adjust dose according to patient's needs. Dosage and treatment recommendations may vary among countries (refer to latest local guidelines).
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Renal Impairment
Severe: Contraindicated.
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Hepatic Impairment
Severe: Contraindicated.
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Administration
Should be taken with food.
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Contraindications
Hyperkalaemia, anuria. Severe renal and hepatic impairment. Concomitant use with other potassium-sparing agents, potassium supplements, potassium salts, potassium-containing salt substitutes or other formulations containing triamterene.
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Special Precautions
Patient with hyperuricaemia or gout; history of renal calculi; diabetes mellitus, depleted folic acid stores. Avoid diuretic use for the treatment of hypertension in patients with primary adrenal insufficiency (Addison's disease). Debilitated or severely ill patient. Elderly. Pregnancy and lactation.
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Adverse Reactions
Significant: Hypersensitivity reaction, photosensitivity, nephrolithiasis; profound diuresis with fluid and electrolyte loss; increased uric acid level (particularly in patients predisposed to gouty arthritis).
Blood and lymphatic system disorders: Thrombocytopenia, megaloblastic anaemia. Gastrointestinal disorders: Nausea, vomiting, diarrhoea, xerostomia. General disorders and administration site conditions: Asthenia, fatigue. Hepatobiliary disorders: Jaundice. Investigations: Liver enzyme abnormalities, increased BUN and serum creatinine. Metabolism and nutrition disorders: Hypokalaemia, metabolic acidosis. Nervous system disorders: Dizziness, headache. Renal and urinary disorders: Azotaemia. Rarely, acute interstitial nephritis and acute renal failure. Skin and subcutaneous tissue disorders: Rash. Potentially Fatal: Hyperkalaemia. |
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Monitoring Parameters
Monitor serum electrolytes (especially potassium), renal function (periodic BUN and serum creatinine determinations), fluid intake and output.
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Overdosage
Symptoms: Electrolyte imbalance (specifically hyperkalaemia), gastrointestinal disturbances (e.g. nausea, vomiting), weakness, hypotension. Management: Administer pressor agents (e.g. norepinephrine) for severe hypotension. Induce emesis or gastric lavage immediately in conscious patients. Carefully evaluate electrolyte pattern and fluid balance and initiate corrective therapy if needed. Dialysis may be of some benefit.
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Drug Interactions
May increase the risk of hyperkalaemia with ACE inhibitors (e.g. captopril, enalapril). Increased risk of renal failure with indometacin. May reduce renal lithium clearance and increase the risk of lithium toxicity.
Potentially Fatal: Increased risk of hyperkalaemia with other potassium-sparing diuretics (e.g. spironolactone, amiloride), potassium supplements, potassium salts or potassium-containing salt substitutes. |
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Lab Interference
May result in false-negative aldosterone/renin ratio (ARR). May interfere with the fluorometric assay of quinidine and methods of enzyme assay that depend on fluorometry (e.g. determinations of lactic dehydrogenase activity).
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Action
Description:
Mechanism of Action: Triamterene is a weak potassium-sparing diuretic that acts directly on the distal renal tubule. It inhibits the reabsorption of sodium ions and decreases the excretion of potassium and hydrogen ions. Onset: Diuresis: 2-4 hours. Duration: Diuresis: 7-9 hours. Pharmacokinetics: Absorption: Rapidly absorbed from the gastrointestinal tract, but the degree of absorption may vary in different patients. Bioavailability: Approx 50%. Time to peak plasma concentration: Approx 3 hours. Distribution: Crosses the placenta. Plasma protein binding: Approx 67%. Metabolism: Extensively metabolised by CYPA12 isoenzyme to 6-p-hydroxytriamterene and its sulfate conjugate. Excretion: Via urine (21-<50%; mainly as metabolites). Plasma half-life: Approx 2 hours. |
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Chemical Structure
 Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 5546, Triamterene. https://pubchem.ncbi.nlm.nih.gov/compound/Triamterene. Accessed Mar. 22, 2024. |
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Storage
Store between 15-30°C. Protect from light.
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MIMS Class
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ATC Classification
C03DB02 - triamterene ; Belongs to the class of other potassium-sparing agents. Used as diuretics.
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References
Anon. Triamterene. AHFS Clinical Drug Information [online]. Bethesda, MD. American Society of Health-System Pharmacists, Inc. https://www.ahfscdi.com. Accessed 19/02/2024. Anon. Triamterene. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 19/02/2024. Buckingham R (ed). Triamterene. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 19/02/2024. Joint Formulary Committee. Triamterene. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 19/02/2024. Triamterene Capsules (TruPharma LLC). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed. Accessed 19/02/2024. Triamterene. Gold Standard Drug Database in ClinicalKey [online]. Elsevier Inc. https://www.clinicalkey.com. Accessed 14/03/2024.
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