Long-acting and short-acting diuretics in the treatment of hypertension.

A single-blind trial was carried out in 36 people with mild to moderate hypertension to compare the efficacy and tolerance of long-term treatment with furosemide and chlorthalidone. After a 30-day wash-out period, patients were treated for 6 months with a single daily dose of either 25 mg furosemide or 50 mg chlorthalidone. They were then crossed over to the alternative drug, after a 15-day wash-out period, for a further 6 months. Results from the 25 patients who completed the study period showed that both treatments were successful in reducing systolic and diastolic blood pressure significantly after 1 month and blood pressure was controlled at the lower level for the remainder of the study period. There was no statistically significant difference between the two treatments at the end of the trial in respect of their antihypertensive efficacy. However, patients on chlorthalidone showed a marked, significant decrease in serum potassium levels from 1 month onwards compared to patients treated with furosemide and at the end of 6 months 10 (25%) were considered to be hypokalaemic whereas only 2 (8%) of the furosemide-treated patients had serum potassium levels lower than 3.5 mmol/l. Few side-effects were reported and patient compliance was good in both treatment groups.