Adherence to Calcium Channel Blocker Therapy in Older Adults: A Comparison of Amlodipine and Felodipine

Abstract

The efficacy of dihydropyridine calcium channel blockers for treating hypertension appears to be similar, but a variety of factors, including patient characteristics, tolerability and pharmacokinetic properties, may influence treatment adherence and outcome. We aimed to evaluate treatment adherence in clinical practice among older hypertensive adults (50+ years) prescribed amlodipine or felodipine for the first time as part of the California Medicaid (Medi-Cal) program. We used a retrospective, matched, cohort-analysis design. Over 1 year, patients prescribed amlodipine were 21% less likely to discontinue study treatment than those prescribed felodipine. Discontinuation tended to occur early, with 20% and 30% of amlodipine and felodipine patients, respectively, discontinuing treatment after one prescription. A non-significant difference in favour of amlodipine was demonstrated for anti-anginal medication use among patients taking these drugs at baseline. This study suggests that use of amlodipine may be associated with improved adherence, compared with felodipine, among older out-patients in the Medi-Cal program.