1983 Volume 20 Issue 6 Pages 491-499
The blood pressure response to the treatment with either spironolactone (75mg/day) or trichlormethiazide (4mg/day) was studied in crossover fashion in 41 old hypertensive patients with mean age of 73 years. One drug was given for 4 weeks and after washout for 2 weeks, the other was given for 4 weeks. Plasma renin activity (PRA), plasma aldosterone concentration (PAC), hematocrit, plasma dry weight and plasma potassium levels were determined at the completion of each treatment period. Both drugs were equally effective in decreasing the blood pressure and they were more effetive in patients whose PRA before treatment had been below 1.0ng/ml/h (n=22) than in those with PRA above 1.1ng/ml/h (n=19). The PRA and PAC increased after both diuretics two to three times compared with basal value. When patients whose mean blood pressure had been decreased by more than 10mmHg during treatment were defined as responders, their PRA was significantly lower than that of nonresponders, before and during treatment, while PAC was not significantly different between these two groups. There was a significant negative correlation between PRA and fall in mean blood pressure during both drugs. The increase in plasma dry weight was significantly higher during the treatment with trichlormethiazide in the blood pressure nonresponder group compared with the responder group, and there was there was a weak negative correlation (r=-0.39, n=41) between increase in plasma dry weight and fall in mean blood pressure during trichlormethiazide. These results suggest that plasma volume depletion might negatively correlate to fall in mean blood pressure, and that the failure to respond to diruetics might be due to sustained elevation of PRA induced by plasma volume depletion. Plasma potassium decreased significantly after trichlormethiazide treatment. Hypokalemia below 3.0mEq/l occured 7 out of 41 patients (17%). The incidence was more frequent significantly in the bedridden patients.