Treatment of benign essential hypertension with frusemide in different doses.

A double-blind, randomized, crossover trial was carried out in 26 hypertensive patients to investigate the hypotensive effects of three different dosages of frusemide (40 mg, 60 mg, and 80 mg twice daily) and the effects on serum potassium and urinary output. The study included a 4-week treatment period with placebo, three periods of 6 weeks with frusemide, and an intervening placebo period of 4 weeks. The mean arterial blood pressure fell about 10 mmHg within the first 2 weeks and was independent of the frusemide dosage. During the following weeks of treatment, there was a constant, slow fall in blood pressure. The period on placebo was too brief for values to return to the initial level. In contrast, the increase in urinary output, which was dose-dependent, ceased when medication was withdrawn. The diuretic effect was maintained throughout the treatment periods. There was a correlation between the fall in serum potassium and the diuretic effect whereas no correlation with the fall in blood pressure could be shown. Except for a significant increase in serum zinc, no changes were observed in other electrolyte parameters. Body weight, pulse, haemoglobin and erythrocyte sedimentation rate remained unchanged. Side-effects were few and mild, but tended to increase with higher doses.