Home Drug Guide Spironolactone

Drug Guide

Generic Name

Spironolactone

Brand Names Aldactone, Carospir

Classification

Therapeutic: Diuretic, antihypertensive, aldosterone antagonist

Pharmacological: Aldosterone receptor antagonist, potassium-sparing diuretic

FDA Approved Indications

Edematous conditions (e.g., heart failure, liver cirrhosis, nephrotic syndrome)
Hypertension
Primary hyperaldosteronism
Acne vulgaris (off-label)
Hormonal therapy for transgender women (off-label)

Mechanism of Action

Spironolactone competitively binds to aldosterone receptors in the distal convoluted tubules of the nephron, reducing sodium reabsorption and potassium excretion, leading to diuresis and decreased blood volume. It also has anti-androgen effects.

Dosage and Administration

Adult: Typically 25-200 mg daily in single or divided doses, adjusted based on clinical response.

Pediatric: Dosing based on weight and condition, usually starting at 2 mg/kg/day, up to a maximum of 4 mg/kg/day.

Geriatric: Start at lower doses due to increased susceptibility to side effects, monitor potassium and kidney function.

Renal Impairment: Use with caution; may require dose adjustments and close monitoring.

Hepatic Impairment: Use with caution; hepatic metabolism may be affected.

Pharmacokinetics

Absorption: Well absorbed orally.

Distribution: Widely distributed in body tissues, crosses the placenta and enters breast milk.

Metabolism: Extensively metabolized in the liver to active and inactive metabolites.

Excretion: Eliminated mainly via urine and feces.

Half Life: Approximately 1.3 to 2 days (longer in patients with renal impairment).

Contraindications

Hyperkalemia
Anuria
Significant renal impairment
Addison's disease

Precautions

Monitor serum potassium and renal function regularly.
Use caution in patients with renal dysfunction, hepatic impairment, or concomitant use of other potassium-sparing agents.

Adverse Reactions - Common

Hyperkalemia (Common)
Gastrointestinal disturbances (nausea, vomiting, diarrhea) (Common)
Dizziness, fatigue (Common)

Adverse Reactions - Serious

Gynecomastia in men (Uncommon)
Severe hyperkalemia leading to cardiac arrhythmias (Rare)
Electrolyte imbalances (Rare)

Drug-Drug Interactions

Potassium supplements, ACE inhibitors, ARBs, NSAIDs (may increase hyperkalemia risk)
Other diuretics

Drug-Food Interactions

Potassium-rich foods (monitor potassium levels)

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor serum potassium, renal function, blood pressure, and fluid status.

Diagnoses:

Risk for electrolyte imbalance
Risk for dehydration

Implementation: Administer with food to reduce gastrointestinal upset. Educate patients about signs of hyperkalemia.

Evaluation: Assess for efficacy in controlling edema/hypertension and monitor adverse effects.

Patient/Family Teaching

Instruct on the importance of regular blood tests to monitor potassium and kidney function.
Advise to avoid potassium-rich foods and potassium supplements unless directed by healthcare provider.
Report symptoms of hyperkalemia such as muscle weakness, irregular heartbeat.

Special Considerations

Black Box Warnings:

Serious hyperkalemia may occur, especially in patients with renal impairment or with concomitant use of other hyperkalemia-inducing drugs.

Genetic Factors: Consider pharmacogenomics for androgen-related side effects.

Lab Test Interference: May cause false rise in serum testosterone measurement.

Overdose Management

Signs/Symptoms: Hyperkalemia, dizziness, hypotension, dehydration.

Treatment: Discontinue medication, administer calcium gluconate for cardiac stabilization if needed, initiate potassium-lowering therapies, initiate IV fluids, and monitor ECG.

Storage and Handling

Storage: Store at room temperature away from moisture and heat.

Stability: Stable under recommended storage conditions.