Biochemical changes in black and Indian hypertensive patients on diuretic therapy.

Thirty-seven patients (19 Blacks and 18 Indians) suffering from mild hypertension were given each of five diuretics separately for 4 weeks after a 'washout' period on placebo of the same duration. The diuretics used were hydrochlorothiazide 25 mg/d (Dichlotride; Frosst MSD), hydrochlorothiazide 25 mg plus triamterene 50 mg (Dyazide; SKF) 1 tablet per day, amiloride hydrochloride 5 mg plus hydrochlorothiazide 50 mg (Moduretic; MSD) 1 tablet per day, chlorthalidone (Hygroton; Geigy) 50 mg/d and indapamide (Natrilix; Servier) 2.5 mg/d. The study showed that during the acute phase of diuretic therapy for the treatment of hypertension plasma potassium levels were decreased by thiazide and thiazide-like diuretics and increased by potassium-sparing diuretics. However, despite the decrease in plasma potassium levels produced by thiazide diuretics and indapamide these levels did not fall to 3.0 mmol/l or less. All the diuretics were effective in lowering the standing mean arterial pressure when compared with placebo values. In the absence of significant hypokalaemia, the choice of a diuretic for the Black hypertensive patient should therefore be determined by its cost.