Is it ever appropriate for a patient with hypertension to take chlorthalidone (a diuretic medication) every other day?

From the Guidelines

Yes, there are valid reasons to prescribe chlorthalidone every other day for some hypertensive patients. This approach is primarily used for patients who need the drug's antihypertensive benefits but experience side effects or have concerns about daily dosing. Chlorthalidone has a long half-life of 40-60 hours, which allows for effective blood pressure control even with alternate-day dosing, as noted in the 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults 1.

Key Considerations

• The typical dose remains 12.5-25 mg, but given every other day instead of daily.
• This schedule may be particularly beneficial for elderly patients or those with reduced kidney function who are more susceptible to electrolyte imbalances, especially hypokalemia.
• Alternate-day dosing can also help minimize metabolic side effects like hyperglycemia, hyperlipidemia, and hyperuricemia while still providing adequate blood pressure control.
• Regular monitoring of blood pressure, electrolytes (particularly potassium), and renal function is necessary to ensure efficacy and safety, as emphasized in the guideline 1.
• If blood pressure control becomes inadequate with alternate-day dosing, the regimen should be reassessed and potentially adjusted back to daily dosing or combined with other antihypertensive medications.

Monitoring and Adjustments

• Patients on chlorthalidone every other day should be closely monitored for signs of hypokalemia, hyperuricemia, and other metabolic side effects.
• The guideline also notes the importance of monitoring for hyponatremia and hypokalemia, uric acid and calcium levels in patients on chlorthalidone 1.
• Adjustments to the dosing regimen may be necessary based on individual patient response and tolerance to the medication.

From the FDA Drug Label

DOSAGE AND ADMINISTRATION ... Edema Initiation Adults, initially 50 to 100 mg daily, or 100 mg on alternate days. The answer is yes, it is appropriate for a patient to take chlorthalidone every other day, but only for edema and with a dose of 100 mg on alternate days. For hypertension, the recommended dosing is daily, with no mention of every other day dosing. 2

From the Research

Dosage Frequency of Chlorthalidone

• The provided studies do not directly address the appropriateness of taking chlorthalidone every other day for patients with hypertension 3, 4, 5, 6, 7.
• However, the studies suggest that chlorthalidone is a effective antihypertensive medication, particularly when compared to hydrochlorothiazide 4, 7.
• One study compared the effects of chlorthalidone and hydrochlorothiazide on ambulatory and office blood pressure, and found that chlorthalidone was more effective in lowering systolic blood pressure 4.
• Another study discussed the use of chlorthalidone as add-on therapy for hypertension, and found that it was effective in reducing blood pressure and had pleiotropic effects beyond blood pressure reduction 7.

Alternative Dosage Schedules

• A study on captopril, a different antihypertensive medication, found that twice daily and three times daily dosing schedules were equally effective in reducing blood pressure 5.
• However, this study does not provide direct evidence for the use of chlorthalidone every other day, and its findings may not be applicable to chlorthalidone 5.

Clinical Practice

• The studies suggest that chlorthalidone is often used as part of a combination therapy regimen, and that it may be more effective than hydrochlorothiazide in certain cases 3, 6, 7.
• However, the optimal dosage frequency of chlorthalidone is not addressed in the provided studies, and its use every other day is not explicitly recommended or discouraged 3, 4, 5, 6, 7.