Comparison of patient compliance with once-daily and twice-daily antibiotic regimens in respiratory tract infections: results of a randomized trial

Background. Patient compliance seems to be highly dependent on the number of daily doses. However, it is unclear whether this effect is still present in the case of infrequent regimens during short-term antibiotic treatment. The aim of this study was to find out whether a once-daily antibiotic regimen provides better patient compliance in the case of common respiratory tract infections than a twice-daily regimen. Methods: Outpatients with acute bacterial exacerbation of chronic bronchitis were treated with clarithromycin 250 mg twice daily or clarithromycin in modified release formulation 500 mg once daily, for 7 days in a prospective, randomized, single-centre study. Patient compliance was assessed with electronic monitoring. Results: Of 122 patients randomized, 119 were evaluable (58 in the once-daily group and 61 in the twice-daily group). All the studied parameters indicated significantly better compliance with the once-daily versus twice-daily antibiotic formulation: overall compliance (93.7% versus 81.3%, P < 0.0001), days with correct number of doses taken (80.3% versus 68.6%, P< 0.0001), correct interdose intervals (74.4% versus 56.4%, P< 0.001), and the mean interdose intervals (95.6% versus 106.3% of the expected values, P < 0.001). Conclusions: The study has proved much better patient compliance with a once-daily versus a twice-daily antibiotic regimen. This effect has been marked in both dosing and timing compliance. These findings indicate the clinical usefulness of a once-daily antibiotic regimen in assuring patient compliance during the treatment of respiratory tract infections.