Antihypertensive efficacy and safety of manidipine versus amlodipine in elderly subjects with isolated systolic hypertension: MAISH study

Background and objective: Isolated systolic hypertension (ISH) affects 10-20% of the elderly population and is strongly related to the risk of cardiovascular events. Elevated systolic BP values are primarily caused by reduced large vessel compliance with a consequent increase in total peripheral resistance. Vasodilating drugs, such as calcium channel antagonists, have proven to be effective in controlling ISH in elderly patients. This study set out to compare the antihypertensive efficacy and safety of two different calcium channel antagonists, manidipine and amlodipine, administered once daily in elderly subjects with ISH. Methods: In a European, randomised, double-blind, multicentre, parallel-group study, after a 2-week placebo run-in period, 195 patients aged ≥60 years with ISH received manidipine 10-20mg once daily or amlodipine 5-10mg once daily. Chlortalidone 25mg once daily could be added to the high dose of test drug in the event of insufficient antihypertensive control. The primary efficacy parameter was the proportion of patients with a reduction in office sitting systolic BP (SBP) ≥15mm Hg, measured at trough, at the final visit. Secondary efficacy parameters included: the proportion of patients with a normal sitting SBP value (<140mm Hg) at the final visit; a change from baseline to the final visit in mean office trough sitting SBP; a change from baseline to the final visit in the cardiovascular risk score as measured by the INDANA (INdividual Data ANalysis of Antihypertensive intervention trials) project score; the proportion of patients with at least a two-point reduction in the cardiovascular risk score; the percentage of patients requiring upward dose titration and diuretic add-on treatment and the investigator's final judgement. Safety and tolerability evaluations were based on adverse events, ECG and laboratory tests, and clinically relevant reports of abnormalities. Results: In the intention-to-treat population (n = 189), 76% and 72% of patients in the manidipine and amlodipine groups, respectively, had a reduction in sitting SBP of ≥15mm Hg (p-value not significant for between-group comparison). The percentage of patients with a normal sitting SBP value was 52% in the manidipine group and 51% in the amlodipine group (p-value not significant for between-group comparison). Sitting SBP reductions at the end of treatment were -19.5 ± 11.8mm Hg in patients receiving manidipine and -18.4 ± 11.1mm Hg in patients receiving amlodipine. Both treatments induced a small reduction in cardiovascular risk score, with 45% of patients in both treatment groups having a two-point reduction in the final score. At the final visit, approximately half of the patients in both treatment groups were still being treated with the low dose of one of the test drugs (manidipine 10mg or amlodipine 5mg). Chlortalidone was added to the high dose of test drugs in 7% and 11% of patients in the amlodipine and manidipine groups, respectively. Both drugs were well tolerated, with a higher incidence of oedema in the amlodipine group (9% vs 4%). No clinically relevant changes in heart rate were induced by either treatment. Conclusion: In elderly patients with ISH, treatment with manidipine for 12 weeks was well tolerated and effective and the antihypertensive effects obtained with manidipine were the same as those obtained with amlodipine.