triamterene

triamterene

(trye am' ter een)

Dyrenium

Pregnancy Category B

Drug class

Potassium-sparing diuretic

Therapeutic actions

Inhibits sodium reabsorption in the renal distal tubule, causing loss of sodium and water and retention of potassium.

Indications

·        Edema associated with CHF, nephrotic syndrome, hepatic cirrhosis; steroid-induced edema, edema from secondary hyperaldosteronism (alone or with other diuretics for added diuretic or antikaliuretic effects), hypertension

Contraindications and cautions

·        Contraindicated with allergy to triamterene, hyperkalemia, renal disease (except nephrosis), liver disease, lactation.

·        Use cautiously with diabetes mellitus, pregnancy.

Available forms

Capsules—50, 100 mg

Dosages

ADULTS

100 mg bid PO if used alone after meals. Reduce dosage if added to other diuretic or antihypertensive therapy. Maintenance dosage should be individualized, may be as low as 100 mg every other day. Do not exceed 300 mg/day.

Hypertension: Start with 25 mg PO once daily; usual dose 50–100 mg/day.

PEDIATRIC PATIENTS

Safety and efficacy not established.

Pharmacokinetics

Route	Onset	Peak	Duration
Oral	2–4 hr	6–8 hr	12–16 hr

Metabolism: Hepatic; T_1/2: 3 hr

Distribution: Crosses placenta; enters breast milk

Excretion: Urine

Adverse effects

·        CNS: Headache, drowsiness, fatigue, weakness

·        Dermatologic: Rash, photosensitivity

·        GI: Nausea, anorexia, vomiting, dry mouth, diarrhea

·        GU: Renal stones, interstitial nephritis

·        Hematologic: Hyperkalemia, blood dyscrasias

Interactions

Drug-drug

·        Increased hyperkalemia with potassium supplements, diets rich in potassium, ACE inhibitors

·        Increased serum levels and possible toxicity with cimetidine, indomethacin, lithium

·        Increased risk of amantadine toxicity

Drug-lab test

·        Interference with fluorescent measurement of serum quinidine levels

Nursing considerations

Assessment

·        History: Allergy to triamterene, hyperkalemia, renal or liver disease, diabetes mellitus, pregnancy, lactation

·        Physical: Skin color, lesions, edema; orientation, reflexes, muscle strength; pulses, baseline ECG, BP; R, pattern, adventitious sounds; liver evaluation, bowel sounds; urinary output patterns; CBC, serum electrolytes, blood sugar, LFTs, renal function tests, urinalysis

Interventions

·        Administer with food or milk if GI upset occurs.

·        Mark calendars or provide other reminders of drug days for outpatients if alternate-day or 3- to 5-day/wk therapy is optimal for treating edema.

·        Administer early in the day so that increased urination does not disturb sleep.

·        Measure and record regular weights to monitor mobilization of edema fluid.

·        Arrange for regular evaluation of serum electrolytes and BUN.

Teaching points

·        Record alternate-day therapy on a calendar, or make dated envelopes. Take the drug early in the day as increased urination will occur. The drug may be taken with food or meals if GI upset occurs.

·        Weigh yourself on a regular basis, at the same time and in the same clothing, and record the weight on your calendar.

·        You may experience these side effects: Increased volume and frequency of urination; drowsiness (avoid rapid position changes; do not engage in hazardous activities such as driving a car; this problem is often made worse by the use of alcohol); avoid foods that are rich in potassium (eg, fruits, Sanka); sensitivity to sunlight and bright lights (wear sunglasses, use sunscreens and protective clothing).

·        Report weight change of more than 3 pounds in 1 day, swelling in ankles or fingers, fever, sore throat, mouth sores, unusual bleeding or bruising, dizziness, trembling, numbness, fatigue.

Adverse effects in Italic are most common; those in Bold are life-threatening.