Multicentric, clinical trial of S-Amlodipine 2.5 mg versus Amlodipine 5 mg in the treatment of mild to moderate hypertension--a randomized, double-blind clinical trial.

OBJECTIVE: To compare the efficacy and tolerability of 2.5 mg of S-Amlodipine with 5 mg of Amlodipine in the treatment of mild to moderate hypertension in a double blind, double dummy, randomized, comparative clinical trial.

METHOD AND MATERIALS: Two hundred OPD patients (97 women and 103 men) with mean age 53.4 +/- 5.58 years, with stage I and stage 2 hypertension were enrolled for the study after obtaining informed written consent. Twelve patients were dropped out as lost to follow up. Ninety seven patients in the S-Amlodipine 2.5 mg treatment group and ninety one patients in the Amlodipine 5 mg treatment group completed the study. Those with a history of angina pectoris, myocardial infarction or recent cerebrovascular accident in the past six months and those with stage 3 and stage 4 hypertension were excluded from the study. Those showing a history of secondary hypertension were also excluded from the study. For the first two weeks all patients received dummy tablets of both S-Amlodipine and Amlodipine, as a wash out therapy and to get the actual blood pressure reading. After two weeks, enrolled patients received a preparation containing either S-Amlodipine (containing 2.5 mg of S-Amlodipine) and dummy tablets of Amlodipine or Amlodipine besylate (containing 5 mg of racemic Amlodipine) and dummy tablets of S-Amlodipine once daily for a period of six weeks.

RESULTS: The results were analyzed by Student's 't' test The reduction in the average systolic and diastolic blood pressure, in the standing, supine and sitting postures in the S-Amlodipine group as well as in the Amlodipine group after six weeks of treatment was highly significant (P < or = 0.0001). The baseline values for average systolic blood pressure in standing, supine and sitting positions in the S-Amlodipine 2.5 mg treatment group were found to be 164.12 +/- 10.28, 165.72 +/- 10.88 and 165.24 +/- 10.66 mm of Hg respectively, which after treatment of six weeks changed to 144.9 +/- 7.4, 146.04 +/- 8.56 and 145.36 +/- 8.32 mm of Hg. The baseline values for average systolic blood pressure in standing, supine and sitting positions in the Amlodipine 5 mg treatment group were found to be 164.57 +/- 10.36, 166.47 +/- 10.58 and 165.81 +/- 10.54 mm of Hg respectively, which after treatment of six weeks changed to 154.42 +/- 6.33, 147.23 +/- 7.11 and 146.57 +/- 7.54 mm of Hg. The baseline values for average diastolic blood pressure in standing, supine and sitting positions in the S-Amlodipine 2.5 mg treatment group were found to be 99.63 +/- 6.22, 101.13 +/- 7.18 and 100.59 +/- 6.6 mm of Hg respectively, which after treatment of six weeks changed to 86.0 +/- 4.70, 87.18 +/- 5.20 and 86.27 +/- 5.68 mm of Hg. While the baseline values for average diastolic blood pressure in standing, supine and sitting positions in the Amlodipine 5 mg treatment group were found to be 98.95 +/- 5.54, 100.86 +/- 6.71 and 100.38 +/- 6.38 mm of Hg respectively, which after treatment of six weeks changed to 86.19 +/- 4.77, 87.52 +/- 5.44 and 87.33 +/- 5.98 mm of Hg. However the difference in the average reduction in systolic and diastolic blood pressures, in the two treatment groups, in the sitting, supine and the standing positions was not found to be statistically significant (p > 0.1) (CI = 0.95). There was no statistically significant change in the levels of serum creatinine, SGOT, SGPT, HDL, LDL, triglyceride and total cholesterol in patients receiving Amlodipine 5 mg. The reduction in total cholesterol as well as triglyceride level in the S-Amlodipine 2.5 mg treatment group was found to be greater but it failed to show any statistically significant difference.

CONCLUSION: S-Amlodipine 2.5 mg is found to be equivalent in its efficacy and tolerability when compared to Amlodipine 5 mg in the treatment of mild to moderate hypertension.