Comparison of first-line antihypertensive drugs by a randomized cross-over method--a preliminary report

The present study was undertaken to compare the effects of first-line antihypertensive drugs in Japanese patients. Four antihypertensive drugs were studied: trichlormethiazide (TCT), nifedipine retard (NIF), atenolol (ATN), and enalapril malate (ENP). Thirty-eight patients (16 men and 22 women; age, 53.3 +/- 8.8 years, mean +/- SD) were enrolled in the study. After a control period of 2 to 4 weeks, the four drugs were administered according to a randomized, cross-over design, the duration of each treatment period being 8 to 12 weeks. The initial dose of each drug was increased until blood pressure (BP) fell to less than 150/90 mmHg. The maximum doses of TCT, NIF, ATN, and ENP were 4, 40, 50, and 20 mg/day, respectively. The protocol was completed in 25 of the 38 patients. The BPs (SBP/DBP) at the end of each period were 168 +/- 3 (mean +/- SEM)/105 +/- 1 (control), 149 +/- 4/ 98 +/- 2 (TCT), 138 +/- 3/89 +/- 2 (NIF), 151 +/- 4/94 +/- 2 (ATN), and 152 +/- 4/97 +/- 2 mmHg (ENP). The BP during NIF treatment was significantly lower than during the other treatments. This finding suggests that the calcium antagonist had a greater hypotensive effect than the other first-line antihypertensive drugs studied. The subjects seem to more closely resemble black rather than white populations with respect to their response to antihypertensive treatment.