[Predictability and prevention of hypokalemia induced by hydrochlorothiazide]

In a double blind study, 104 hypertensive patients were randomly allocated to two different stepped care programs for 6 months. Following a placebo run-in-phase, patients were given either Enalapril (EN) 20 mg once-a-day, or a Placebo (PL). Drugs were added as follow in a parallel stepwise sequence, until the goal blood pressure was obtained. First Hydrochlorothiazide (HCTZ) and then, if necessary, Oxprenolol (OXP) and Dihydralazine (DIH). The two goals of this study were to lower diastolic blood pressure below 90 mmHg and to maintain plasma potassium above 3.5 mmol/l. Amiloride was prescribed if plasma potassium was lower than 3.5 mmol/l. At the end of the study the EN group's blood pressure was 130 +/- 12/83 +/- 6 mmHg, the tablet's daily number was 2.6 +/- 1.8 and Amiloride was necessary in 15 patients. These parameters were significantly different from those observed in the Pl group (BP: 136 +/- 9/87 +/- 5 mmHg, tablets 4.2 +/- 2.4; amiloride necessary in 34 patients). The effects of HCTZ were evaluated in 32 patients previously treated by EN compared to 39 patients receiving PL. The converting enzyme inhibition minimized the fall in plasma potassium induced by HCTZ (3.6 t +/- 0.4 vs 3.3 +/- 0.5 mmol/l, p less than 0.05). Related to the HCTZ dose (mg/kg), the plasma potassium fall is lower in the EN group (0.46 +/- 1.1) than in the PL group (0.94 +/- 0.9, p less than 0.05). The plasma potassium reduction could not be predicted by age, plasma renin activity, plasma and urinary aldosterone or urinary kallikrein.(ABSTRACT TRUNCATED AT 250 WORDS)