Effect of Hydrochlorothiazide and Chlorthalidone on Recently Diagnosed Hypertensives: A Comparative Approach

Background: Hydrochlorthiazide and chlorthalidone are the two thiazides which are routinely used in hypertension. Metabolic abnormities especially hypokalaemia can be minimsed with the use of chlorthalidone which is more potent and longer acting.

Objective: Thiazide diuretics have been the first choice to treat stable, uncomplicated, essential hypertension; hydrochlorothiazide (HCTZ) being the most preferred. Another thiazide, chlorthalidone is available since long and is reported to be equally efficacious if not better in treating primary hypertension.

Aim: To compare the efficacy and safety of HCTZ and chlorthalidone in the management of primary essential hypertension.

Methods: We compared these two drugs in a randomized, single-blinded, intention to treat study. Participants with essential hypertension received either chlorthalidone 12.5 mg OD or HCTZ 25 mg OD for a period of 12-week. The results were compared on the basis of 12 hourly ambulatory blood pressure (BP) monitoring; fortnightly record of serum potassium, and failure of treatment (i.e., the need of additional antihypertensive drug or incrementation in the dose of thiazides).

Results: Out of 114,44 in chlorthalidone group and 39 in HCTZ group completed our study. There was a significant mean fall in BP by -11.89/-9.86 in the morning time and by -11.12/-7.56 in the evening time in group H receiving HCTZ 25 mg OD. In chlorthalidone group, this mean fall was by-16.45/-12.38 in the morning time and by -15.73/-10.86 in the evening time. After 12 weeks, night time BP control was better in chlorthalidone group (127.91±5.01) than HCTZ (132.67±5.19) (p=0.001). Both drugs decreased serum potassium levels, but this decrease was marginally more with HCTZ (3.777±0.601 vs. 3.891±0.534), statistically non-significant when compared to each other (p>0.05).

Conclusion: Chlorthalidone is better than HCTZ in controlling BP throughout the day without causing any significant complication.