Spironolactone Dosing Frequency
Spironolactone is typically administered as a single daily dose, not divided into 6-hourly or 12-hourly regimens. 1
Standard Dosing Regimen
- The usual diuretic regimen consists of a single morning dose of oral spironolactone, typically starting at 100 mg daily when used for ascites in cirrhosis 1
- For heart failure, treatment is initiated at 25 mg once daily with potential titration to 50 mg once daily as clinically indicated 2
- For hypertension, the recommended initial daily dose is 25-100 mg administered as a single dose 2
- Single morning dosing maximizes patient compliance compared to multiple daily doses 1
Pharmacokinetic Considerations
- Spironolactone has a long half-life, which allows for once-daily dosing 1
- The drug can be taken with or without food, but should be taken consistently with respect to food intake 2
- Despite its long half-life, the drug's effects are maintained throughout a 24-hour period, eliminating the need for multiple daily doses 3
Special Clinical Scenarios
- For patients with renal impairment (eGFR between 30-50 mL/min/1.73m²), dosing may be reduced to 25 mg every other day due to increased risk of hyperkalemia 1, 2
- In patients with cirrhosis, therapy should be initiated in a hospital setting with slow titration, with doses ranging from 25-200 mg daily as a single dose 2
- For acne treatment in women, doses typically range from 50-200 mg daily, administered once daily in the evening 1
Monitoring Considerations
- Potassium and renal function should be monitored before starting treatment, at 1 and 4 weeks after initiation, and after any dose increase 4
- If potassium rises to >5.5 mmol/L, the dose should be halved and monitored closely 4
- If potassium rises to ≥6.0 mmol/L, spironolactone should be stopped immediately 4
Common Side Effects with Once-Daily Dosing
- Hyperkalemia (particularly in elderly patients and those with renal impairment) 4
- Menstrual irregularities (in 40.6% of women) 1
- Breast tenderness and gynecomastia (more common in men) 4
- Dizziness, fatigue, and headache 1
The evidence consistently supports once-daily dosing of spironolactone across various indications, with no recommendations for 6-hourly or 12-hourly administration in any of the major clinical guidelines.