Aliskiren Boosts Diuretic's Benefit

Plasma renin concentrations rose from baseline in all patients,. The largest increases were in patients who received both antihypertensive drugs. On average, renin concentration rose by 348%, compared with baseline, in patients who took 300 mg of aliskiren daily, by 108% in patients who received 25 mg of hydrochlorothiazide daily, and by more than 1200% in patients who received both dosages simultaneously. (See box.)

But the data also showed that aliskiren was effective at blocking renin activity. Plasma renin activity fell by an average of 54%–65%, compared with baseline, in patients who took any dosage of aliskiren (75, 150, or 300 mg/day) as monotherapy.

And in those patients treated with any of the combined regimens of aliskiren and hydrochlorothiazide, renin activity dropped by an average of 46%–64%. In contrast, patients treated with 25 mg/day of hydrochlorothiazide alone showed increases in plasma renin activity of 72%, and those who received 12.5 mg/day of hydrochlorothiazide alone had a 45% boost in their plasma renin activity.

Combined treatment with aliskiren appeared to give an “enhanced antihypertensive effect and potentially improved end-organ protection through effective suppression of the renin system,” concluded Dr. Calhoun and his associates in their poster.