THE USE OF SELF-MEASURED BLOOD-PRESSURE DETERMINATIONS IN ASSESSING DYNAMICS OF DRUG COMPLIANCE IN A STUDY WITH AMLODIPINE ONCE-A-DAY, MORNING VERSUS EVENING

Objective: To test whether the time of administration influences the t herapeutic response to a calcium antagonist taken once a day. Also, th e dynamics of drug compliance and its impact on blood pressure control were investigated. Design: Twenty outpatients with mild-to-moderate h ypertension were included in a randomized, placebo-controlled open stu dy. In a crossover design, all of the patients received 5 mg amlodipin e, either in the morning or in the evening, during two consecutive 4-w eek treatment periods. Methods: Blood pressure was taken by casual mea surement, ambulatory 24-h monitoring (SpaceLabs 90202) and self-measur ement at home, performed with a semi-automatic oscillometric device du ring the whole study period. Compliance was assessed using the Medicat ion-Event-Monitoring System (MEMS). Results: Neither casual nor ambula tory day- or night-time readings detected a significant difference bet ween morning and evening administration. However, self-measurement doc umented significantly greater blood pressure reductions for morning th an for evening administration. The MEMS showed different compliance on the days of ambulatory monitoring (100% with both drug regimens) comp ared with the whole treatment period. The number of days with missed m edication was thus significantly higher for the evening dosing regimen . The difference in self-measured blood pressure between the two regim ens was lost if the days with missed medication were removed from the statistical analysis. Conclusions: Time of once-a-day amlodipine admin istration does not influence its efficacy for 24-h blood pressure cont rol. Furthermore, the use of self-measurement and the MEMS may provide useful additional information on the pharmacodynamic impact of differ ent dosing patterns in hypertensive patients.