Can chlorthalidone tablets be cut in half?

Can Chlorthalidone Tablets Be Cut in Half?

Yes, chlorthalidone tablets can be cut in half, particularly the 50 mg scored tablets which are specifically designed for splitting, and this practice is clinically supported given that lower doses (12.5-25 mg) are the recommended starting doses for hypertension management.

Tablet Formulation and Scoring

• The 50 mg chlorthalidone tablets are manufactured as scored tablets, specifically designed to facilitate splitting, with "TP" debossed above the score line and "50" below it 1
• The 25 mg tablets are unscored and round, making them less suitable for splitting 1
• The presence of a score line on the 50 mg tablet is a deliberate pharmaceutical design feature that allows for accurate dose division 1

Clinical Rationale for Dose Splitting

Lower doses of chlorthalidone are actually preferred for initial therapy, making tablet splitting clinically appropriate:

• The recommended starting dose is 12.5-25 mg daily, not the full 50 mg tablet 2
• Multiple guidelines recommend chlorthalidone at 12.5-25 mg once daily as the optimal initial dose 3
• Research demonstrates that 25 mg daily is as effective as 50-75 mg for blood pressure control but causes significantly fewer metabolic side effects [4, 5
• Studies show that 12.5 mg doses can be effective, particularly when combined with other antihypertensives [6, 7

Evidence Supporting Lower Doses

• A multicenter study found that 25 mg chlorthalidone produced blood pressure reductions equivalent to 50 mg and 75 mg doses, but with less potassium depletion and fewer adverse effects 4
• Another study confirmed that 25 mg is the optimum dosage for initiation of therapy, associated with less adverse biochemical changes than higher doses 5
• The 12.5 mg dose has been shown effective in step-down therapy and combination regimens, with reduced side effects [8, 6

Practical Implementation

If you need a 12.5 mg or 25 mg dose:

• Split the 50 mg scored tablet in half to obtain 25 mg 1
• For 12.5 mg dosing, you would need to quarter the 50 mg tablet (though this is less precise) or obtain 25 mg tablets and split those (though they are unscored) 1

Important Caveats

• Electrolyte monitoring is essential within 2-4 weeks of any dose initiation or change, as lower doses cause less hypokalemia and hyponatremia [2, 4
• The maximum recommended dose is 50 mg daily, so splitting is only relevant for achieving lower therapeutic doses 2
• Store tablets in a tight, light-resistant container and protect from light after splitting 1