Concomitant therapy with labetalol and hydrochlorothiazide in moderate to moderately severe essential hypertension

Labetalol is a competitive, nonselective antagonist of both beta 1 and beta 2 adrenoceptors. It has been suggested that labetalol reduces blood pressure (BP) predominantly by decreasing peripheral vascular resistance while maintaining cardiac output. We conducted a double-blind, randomized study to assess the antihypertensive effect of labetalol in patients with a standing diastolic blood pressure (SDBP) between 105 and 119 mm Hg. The study consisted of three separate phases in succession. Phase I was a single-blind, placebo washout phase, two to four weeks in length. Those patients with a SDBP greater than or equal to 105 mm Hg at the end of phase I entered phase II, in which they were administered labetalol in a forced titration of 100 mg bid to 400 mg bid. Those with a SDBP less than or equal to 90 mm Hg on the 400 mg bid regimen for two weeks were maintained on labetalol alone (N = 8). Those patients whose BP was not controlled (SDBP greater than or equal to 99 mm Hg, N = 15) were randomized in a double-blind fashion to receive either hydrochlorothiazide (HCTZ) or placebo in addition to labetalol for the next five weeks. Eight of the 15 patients received HCTZ and seven received placebo. The BPs at baseline and at the end of phase II were similar in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)