Low-dose chlorthalidone superior to low-dose hydrochlorothiazide for sustained BP lowering

In a new study, low-dose chlorthalidone was associated with further reductions in mean 24-hour BP compared with low-dose hydrochlorothiazide in patients with stage 1 hypertension.

Low-dose hydrochlorothiazide is the most commonly prescribed BP-lowering drug in the United States, but it appears to be a short-acting drug.Anil K. Pareek, MD, and colleagues conducted a study to compare whether low-dose chlorthalidone is a better option for reduction of 24-hour BP.

The researchers randomly assigned 54 patients with stage 1 hypertension(mean age, 45 years) to chlorthalidone 6.25 mg, hydrochlorothiazide 12.5 mg or a controlled-release version of hydrochlorothiazide 12.5 mg.

Pareek and colleagues performed 24-hour ambulatory BP monitoring on all patients at baseline, at 4 weeks and at 12 weeks.

At 4 weeks and 12 weeks, all three treatments were associated with lowering of office BP (P < .01 for all), the researchers found.

Sustained BP lowering

Chlorthalidone was associated with lowering of ambulatory systolic BP at 4 weeks (change, –6.74 mm Hg; P = .005) and 12 weeks (change, –12.11 mm Hg; P = .001), and ambulatory diastolic BP at 4 weeks (change, –5.73 mm Hg; P = .013) and 12 weeks (change, –8.74 mm Hg; P = .002). Controlled-release hydrochlorothiazide was associated with similar reductions at the same time points (P for change in systolic BP at 4 weeks = .014; P for change in systolic BP at 12 weeks = .034; P for change in diastolic BP at 4 weeks = .012; P for change in diastolic BP at 12 weeks = .014). However, the association was not similar for conventional hydrochlorothiazide (P for change in systolic BP at 4 weeks = .191; P for change in systolic BP at 12 weeks = .017; P for change in diastolic BP at 4 weeks = .217; P for change in diastolic BP at 12 weeks = .058), according to the results.

Similarly, chlorthalidone and controlled-release hydrochlorothiazide lowered ambulatory nighttime mean systolic BP and diastolic BP at 4 weeks and 12 weeks, but conventional hydrochlorothiazide did not. According to the researchers, nighttime systolic ambulatory BP was lower in the chlorthalidone group vs. the conventional hydrochlorothiazide group at 4 weeks (P = .015) and 12 weeks (P = .02).

“This discrepancy between [ambulatory BP monitoring] and office BP indicates that [hydrochlorothiazide] lowers BP appropriately during the daytime, when patients are seen on the physician’s office, but has little if any effect during the night and early morning hours,” Pareek, president of medical affairs and clinical research at Ipca Laboratories Limited in Mumbai, India, and colleagues wrote. “In contrast to conventional [hydrochlorothiazide], chlorthalidone (and [controlled-release hydrochlorothiazide]) provides smooth BP control throughout the diurnal cycle.”

Long-acting therapies beneficial

The results of this study may not be generalizable because of the small sample size and exclusion of patients aged older than 65 years, Hillel Sternlicht, MD, and George L. Bakris, MD, both from the department of medicine, American Society of Hypertension Comprehensive Hypertension Center, University of Chicago Medicine, wrote in an accompanying editorial.

However, “the clear message is that a low dose of a long-acting diuretic therapy can have a meaningful impact on the management of hypertension and on CV outcomes,” Sternlicht and Bakris, a member of the Cardiology Today Editorial Board, wrote. – by Erik Swain

Disclosure: The study was sponsored by Ipca Laboratories Limited, of which Pareek is an employee. Please see the full study for a list of the other researchers’ relevant financial disclosures. Bakris reports consulting for AbbVie, AstraZeneca, Bayer, Daiichi Sankyo, Janssen Pharmaceuticals, NxStage and Takeda and serving as principal investigator for a trial sponsored by Bayer. Sternlicht reports no relevant financial disclosures.

Source: www.healio.com