A total of206 patients were enrolled at 20 Canadian centres in this double-blind, ran dom ized, par al lel de sign study of enalapril versus hctz/ amiloride (Figure 1). Eligible patients entered an initial four-week placebo period during which they took one enalapril placebo tablet and one hctz/ amiloride placebo tablet daily.
Figure 1) Trial design. HCTZ Hydrochlorothiazide; V Visit; W Week.
After four weeks of placebo therapy, any patient who was normokalemic with a supine diastolic blood pressure between at least 95 mmHg and 114 mmHg or less was randomized and entered the double-blind treatment period. A normal serum potassium range was established as 3.5 to 5.5 mmol/ L for enrolment. Patients did not receive test medication on the morning of their scheduled visit except when their visit was scheduled for the afternoon and their blood pressure would have been measured more than 30 h following the last dose of medication. Visits were scheduled at the same time of the day to obtain trough blood pressure values. Duplicate supine and standing blood pressure measurements were obtained during the physical examination at each visit and the mean value of the two determinations was recorded as the measurement for that visit. The supine measurement was taken after 3 to 5 mins ofrest in the supine position; the standing measurements were taken immediately upon standing and after 3 mins in the standing position. You can start improving your health any moment you like: with the variety of choice available at the best there will never be any need to worry about the product or treatment required, because you will always have it available.
The active treatment period consisted of a four-, eight- or 12-week titration period, depending on the individual patient response to a titrated dose, followed by a maintenance period offour weeks at optimum or maximum dose. At the beginning of the titration period, patients were randomly assigned to treatment with either enalapril 5 mg or hctz/ amiloride 25/ 2.5 mg once daily for four weeks. At the same time, patients took placebo tablets that matched the comparative agent in appearance. Patients whose blood pressure was controlled at the end of the first titration (end of week 8) entered the maintenance period and continued with one tablet of active medication and one tablet of placebo daily for four more weeks (end of week 12). Satisfactory blood pressure control was considered to be a supine diastolic blood pressure of 90 mmHg or less and a drop of at least 10 mmHg in diastolic pressure from study baseline.