Short- and long-term therapy of mild essential hypertension with timolol

The short and long-term antihypertensive action of timolol, a beta blocker, was assessed in 36 mild hypertensives in a 32-wk, double-blind, placebo-controlled study followed by an additional 96 wk of timolol in 17 responders. Diastolic blood pressure (DBP) and heart rate (HR) declined during the first phase from 103 to 93 mm Hg and from 73 to 61 bpm (P < 0.01) but there was no change in systolic blood pressure (SBP). The initial hypotensive responses continued in 17 long-term timolol subjects (DBP 89 mm Hg at 32 wk and 88 mm Hg at 96 wk [NS] and HR 62 and 65 bpm [NS]). Although stimulated plasma renin activity in the entire group decreased from 1.08 to 0.28 ng/ml/hr (P < 0.001), blood pressure reduction did not correlate with this decline (r = 0.29) or with serum timolol level (r = 0.29). In 20 patients who underwent treadmill exercise evaluation, timolol limited exercise HR and duration and work capacity but peak SBP was not altered. Thus, timolol is effective in reducing mild high blood pressure during short-term therapy and in maintaining this effect over the long term in responsive subjects. It is therefore potentially useful in chronic essential hypertension.