March 20th, 2013

Chlorthalidone Associated with More Electrolyte Problems Than Hydrochlorothiazide

The diuretics chlorthalidone and hydrochlorothiazide are similarly effective at preventing cardiovascular events among older adults with hypertension, but electrolyte abnormalities are more common with chlorthalidone, according to a study in the Annals of Internal Medicine.

Canadian researchers used healthcare databases to identify nearly 30,000 adults over age 65 recently prescribed varying doses of chlorthalidone or hydrochlorothiazide. During follow-up, the rate of the primary outcome — a composite of death or hospitalization for MI, stroke, or heart failure — did not differ significantly between the chlorthalidone and hydrochlorothiazide groups (3.2 and 3.4 events per 100 person-years).

Hospitalization for hypokalemia was more likely among chlorthalidone recipients (0.69 vs. 0.27 events per 100 person-years), as was hospitalization for hyponatremia.

The authors conclude that in the absence of a large, randomized trial comparing the two treatments, “it may be reasonable to conclude that hydrochlorothiazide is safer than chlorthalidone in elderly patients at typically prescribed doses.”

Reprinted with permission from Physician’s First Watch

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