Dyrenium

Dyrenium,

trademark for a potassium-sparing diuretic (triamterene).

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triamterene

Dyrenium, Dytac (UK)

Pharmacologic class: Potassium-sparing diuretic

Therapeutic class: Diuretic

Pregnancy risk category B

FDA Boxed Warning

• Abnormal serum potassium elevation may occur, and is more likely in patients with renal impairment or diabetes and in elderly or severely ill patients. As uncorrected hyperkalemia may be fatal, monitor serum potassium levels frequently, especially when dosage is changed or patient has an illness that may influence renal function.

Action

Depresses sodium resorption and potassium excretion in renal distal tubule

Availability

Capsules: 50 mg, 100 mg

⊘Indications and dosages

➣ Edema

Adults: 100 mg P.O. b.i.d. Do not exceed 300 mg/day.

Dosage adjustment

• Concurrent antihypertensive drug therapy
• Elderly patients

Off-label uses

• Diabetes insipidus

Contraindications

• Hypersensitivity to drug
• Hyperkalemia
• Severe hepatic disease
• Anuria, severe renal dysfunction (except nephrosis)
• Concurrent use of other potassium-sparing diuretics or potassium supplements

Precautions

Use cautiously in:
• hepatic dysfunction, renal insufficiency, diabetes mellitus
• history of gout or renal calculi
• elderly or debilitated patients
• pregnant or breastfeeding patients
• children (safety not established).

Administration

• Give after meals.
• Know that drug may be used alone or as adjunct to thiazide or loop diuretics.
• Make sure patient stops taking potassium supplements before starting triamterene.

Route	Onset	Peak	Duration
P.O.	2-4 hr	Unknown	12-16 hr

Adverse reactions

CNS: headache, fatigue, asthenia, dizziness

GI: nausea, vomiting, diarrhea, dry mouth

GU: azotemia, renal calculi

Hematologic: megaloblastic anemia, thrombocytopenia

Hepatic: jaundice

Metabolic: hyperglycemia, hyperkalemia, metabolic acidosis

Skin: rash, photosensitivity

Other: anaphylaxis

Interactions

Drug-drug. Amantadine: increased amantadine blood level, greater risk of toxicity

Angiotensin-converting enzyme inhibitors, cyclosporine, indomethacin, potassium-sparing diuretics, potassium supplements, other potassium-containing preparations: increased risk of hyperkalemia

Antihypertensives, nondepolarizing muscle relaxants, other diuretics, preanesthetic and anesthetic agents: potentiated effects of these drugs

Chlorpropamide: increased risk of hyponatremia

Cimetidine: increased bioavailability and decreased renal clearance of triamterene

Indomethacin: increased risk of acute renal failure

Lithium: decreased lithium clearance, greater risk of lithium toxicity

Drug-diagnostic tests. Alkali reserves, hemoglobin, platelets: decreased values

Blood urea nitrogen (BUN), creatinine, glucose, hepatic enzymes, potassium: increased levels

Liver function tests: increased values

Quinidine blood level: interference with fluorescent measurement

Drug-food. Salt substitutes containing potassium: increased risk of hyperkalemia

Drug-herbs. Gossypol, licorice: increased risk of hypokalemia

Patient monitoring

• Monitor BUN, creatinine, and electrolyte levels. Stay alert for hyperkalemia.
• Assess CBC with white cell differential.

Patient teaching

• Advise patient to take after meals to reduce nausea.
• Instruct patient to take last daily dose in early evening to avoid nocturia.
• Teach patient to recognize and report signs and symptoms of electrolyte imbalances.
• Tell patient to avoid salt substitutes. Advise him not to use herbs without consulting prescriber.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, foods, and herbs mentioned above.