Patient Compliance with Once-Daily and Twice-daily Oral Formulations of 5-Isosorbide Mononitrate: A Comparative Study

This study compares patient compliance with once- and twice-daily formulations of 5-isosorbide mononitrate. A total of 31 patients (20 men and 11 women) with stable angina pectoris were randomized to receive either 60 mg 5-isosorbide mononitrate in a controlled release formulation once daily, or 20 mg 5-isosorbide mononitrate twice daily. The results indicated that compliance assessed using the electronic Medication Event Monitoring System (MEMS®) was better with the once-daily than with the twice-daily formulation; patients on the once-daily regimen performed better with respect to the total number of bottle openings, the number of openings per day, the timing of openings and the intervals between openings. The apparently superior compliance with the once-daily regimen appeared to be reflected in better efficacy; patients on the once-daily regimen experienced fewer angina attacks (a mean of 1.7 per 7 days, compared with 3.3 per 7 days for patients on the twice-daily regimen) and used fewer nitroglycerin tablets than those on the twice-daily regimen.