spironolactone

spironolactone

(speer on oh lak' tone)

Aldactone, Novospiroton (CAN)

Pregnancy Category D

Drug classes

Potassium-sparing diuretic

Aldosterone antagonist

Therapeutic actions

Competitively blocks the effects of aldosterone in the renal tubule, causing loss of sodium and water and retention of potassium.

Indications

·        Diagnosis and maintenance of primary hyperaldosteronism

·        Adjunctive therapy in edema associated with CHF, nephrotic syndrome, hepatic cirrhosis when other therapies are inadequate or inappropriate

·        Treatment of hypokalemia or prevention of hypokalemia in patients who would be at high risk if hypokalemia occurred: Digitalized patients, patients with cardiac arrhythmias

·        Essential hypertension, usually in combination with other drugs

·        Unlabeled uses: Treatment of hirsutism due to its antiandrogenic properties, palliation of symptoms of PMS, treatment of familial male precocious puberty, short-term treatment of acne vulgaris

Contraindications and cautions

·        Contraindicated with allergy to spironolactone, hyperkalemia, renal disease, anuria, amiloride or triamterene use.

·        Use cautiously with pregnancy, lactation.

Available forms

Tablets—25, 50, 100 mg

Dosages

ADULTS

·        Edema: Initially, 100 mg/day (range 25–200 mg/day) when given as the sole agent; continue > 5 days, then adjust dose or add another diuretic or both.

·        Diagnosis of hyperaldosteronism: 400 mg/day PO for 3–4 wk (long test). Correction of hypokalemia and hypertension are presumptive evidence of primary hyperaldosteronism. 400 mg/day PO for 4 days (short test). If serum K⁺ increases but decreases when drug is stopped, presumptive diagnosis can be made.

·        Maintenance therapy for hyperaldosteronism: 100–400 mg/day PO.

·        Essential hypertension: 50–100 mg/day PO. May be combined with other diuretics.

·        Hypokalemia: 25–100 mg/day PO.

PEDIATRIC PATIENTS

·        Edema: 1–3.3 mg/kg/day PO adjusted to patient's response, administered as single or divided dose.

Pharmacokinetics

Route	Onset	Peak	Duration
Oral	24–48 hr	48–72 hr	48–72 hr

Metabolism: Hepatic; T_1/2: 20 hr

Distribution: Crosses placenta; enters breast milk

Excretion: Urine

Adverse effects

·        CNS: Dizziness, headache, drowsiness, fatigue, ataxia, confusion

·        Dermatologic: Rash, urticaria

·        GI: Cramping, diarrhea, dry mouth, thirst, vomiting.

·        GU: Impotence, irregular menses, amenorrhea, postmenopausal bleeding

·        Hematologic: Hyperkalemia, hyponatremia, agranulocytosis

·        Other: Carcinogenic in animals, deepening of the voice, hirsutism, gynecomastia

Interactions

Drug-drug

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

·        Decreased diuretic effect with salicylates

·        Decreased hypoprothrombinemic effect of anticoagulants

Drug-food

·        Increased absorption when taken with food

Drug-lab test

·        Interference with radioimmunoassay for digoxin; false increase in serum digoxin levels

Drug-alternative therapy

·        Decreased effectiveness if combined with licorice therapy

Nursing considerations

Assessment

·        History: Allergy to spironolactone; hyperkalemia; renal disease; pregnancy, lactation

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

Interventions

·        Mark calendars of edema outpatients as reminders of alternate day or 3- to 5-day/wk therapy.

·        Give daily doses early so that increased urination does not interfere with sleep.

·        Make suspension as follows: Tablets may be pulverized and given in cherry syrup for young children. This suspension is stable for 1 mo if refrigerated.

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

·        Avoid giving food rich in potassium.

·        Arrange for regular evaluation of serum electrolytes, BUN.

Teaching points

·        Record alternate-day therapy on a calendar, or prepare dated envelopes. Take the drug early because of increased urination.

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

·        Avoid foods that are rich in potassium (fruits, Sanka); avoid licorice.

·        You may experience these side effects: Increased volume and frequency of urination; dizziness, confusion, feeling faint on arising, drowsiness (avoid rapid position changes, hazardous activities: driving, using alcohol); increased thirst (suck on sugarless lozenges; use frequent mouth care); changes in menstrual cycle, deepening of the voice, impotence, enlargement of the breasts can occur (reversible).

·        Report weight change of more than 3 pounds in one day, swelling in your ankles or fingers, dizziness, trembling, numbness, fatigue, enlargement of breasts, deepening of voice, impotence, muscle weakness or cramps.

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