Clinical equivalence of two tablet formulations of felodipine. A placebo-controlled study of 24-hour blood pressure control and tolerability.

OBJECTIVE: This study was performed to assess whether a new formulation of felodipine extended release (FER) tablets with a 9 mm diameter is similar to the presently used 11 mm diameter FER formulation with respect to antihypertensive effect and tolerability in patients with essential hypertension. A randomised, double-blind, placebo controlled, three-way cross-over study design was used. PATIENTS: Twenty-four patients with a supine diastolic blood pressure (DBP) of 95-115 mmHg after a 4-week placebo run-in period were given FER 5 mg 9 mm tablets, FER 5 mg 11 mm tablets and placebo in randomised order. The tablets were given once daily and each double-blind treatment period lasted for two weeks. METHODS: Twenty-four hour ambulatory blood pressure monitoring was performed at the end of each treatment period. The primary effect variable was mean DBP over 24 hours. Nineteen patients had 24-hour blood pressure data valid for analysis using an analysis of variance with patient, treatment, period and carry-over as factors. RESULTS: Both formulations of FER 5 mg tablets significantly reduced the mean 24-hour DBP compared to placebo. The 9 and 11 mm tablets resulted in, on average, 4.7 and 3.4 mmHg lower mean 24-hour DBP than placebo. There was, however, no significant difference between the two different FER formulations. Both FER formulations were well tolerated and similar to placebo in this respect. CONCLUSION: Both FER 5 mg tablet formulations (9 and 11 mm diameter), given once daily, were clinically equivalent with respect to antihypertensive effect and tolerability in patients with mild to moderate essential hypertension.