Antihypertensive action of drug combination: Timolol, hydralazine, hydrochlorothiazide and triamterene

A fixed combination tablet containing 5 mg of timolol, 25 mg of hydralazine, 25 mg of hydrochlorothiazide and 37.5 mg of triamterene was prepared and its antihypertensive effect compared with placebo in a randomized double-blind cross-over study lasting 16-20 weeks. 37 patients entered the study and 32 of them completed it. The trial drug caused a highly significant drop in blood pressure in both the supine and standing positions (from 172/112 to 142/91 mm Hg supine and from 168/17 to 136/100 mm Hg standing). There was also a highly significant fall in heart rate. Three patients were nonresponders with maximal dose used (4 tablets daily) and two patients had to withdraw from the trial because of complications. In general the side effects recorded were mild and equally common both on placebo and the trial drug. The serum potassium level was well maintained. The serum urate concentration was increased, but no signs of gout were observed. The conclusion was that this fixed combination of timolol, hydralazine, hydrochlorothiazide and triamterene is effective and well tolerated in the treatment of mild to moderate hypertension.