Amlodipine versus extended-release felodipine in general practice: A randomized, parallel-group study in patients with mild-to-moderate hypertension

The efficacy and tolerability of amlodipine and the extended-release (ER) formulation of felodipine were compared in this multicenter, randomized, double-blind, parallel-group, comparative study involving 201 patients with mild-to-moderate hypertension seen in 22 general clinical practices. Patients with a supine diastolic blood pressure (DBP) greater than or equal to 95 and less than or equal to 114 mm Hg were eligible for entry into the study, A 4-week, single-blind, placebo washout period preceded the 12-week active treatment period. Initially the patients were randomly assigned to receive either amlodipine 5 mg or felodipine ER 5 mg once daily, After 4 or 8 weeks the dosage was increased to 10 mg once daily if sitting DBP was greater than or equal to 95 mm Hg; if DBP was still greater than or equal to 95 mm Hg after 4 weeks 10 mg/d of lisinopril was added and the dose of amlodipine or felodipine ER was reduced to 5 mg, The titration period was followed by a maintenance period of 4 to 8 weeks. The primary goals for blood pressure control were a sitting DBP less than or equal to 90 mm Hg or a decrease of at least 10 mm Hg from baseline at the end of treatment without the use of additional medication, the occurrence of serious adverse events, and/or an increased heart rate, A patient was considered a responder if this goal was achieved; on the basis of a pre-set definition, primarily efficacy and tolerability, treatment was defined as successful or unsuccessful, Both drugs effectively reduced blood pressure. There was no significant difference in efficacy between the two drugs; however, 15 patients who received felodipine ER and 7 who received amlodipine required combination therapy with lisinopril; this difference was not statistically significant, The numbers (percentages) of responders/nonresponders were as follows: in the amlodipine group, 69 (68%)/32 (32%) and in the felodipine ER group, 49 (53%)/43 (47%). The differences in responders between groups were statistically significant. The frequency of spontaneously reported adverse events was 33% in the amlodipine group and 42% in the felodipine ER group. Severe adverse events were reported in 2 and 9 patients in the amlodipine and felodipine ER groups, respectively; these differences were statistically significant. Four patients in the amlodipine group and 11 in the felodipine ER group withdrew from the study because of adverse events. Between groups differences for study withdrawal were not significant. Treatment was successful in 48 (50.5%) patients in the amlodipine group and in 33 (37.5%) patients in the felodipine ER group; the difference in success rates was not statistically significant. The successful:unsuccessful rate ratio between the treatment groups was 1.35 (0.96 < relative risk < 1.88). In conclusion, at equipotent antihypertensive doses, amlodipine has a more favorable clinical profile than felodipine.