Methods: Patients with suspected bacterial lower respiratory tract infections, pharyngitis and dental infections were included in the study. Adherence was assessed by electronic monitoring, which recorded every opening of the patient's bottle of pills. The outcome variables were compliance with taking the medication, taking the correct dose and with timing of the dose.

Results: A total of 240 patients were enrolled (167 in the thrice-daily group and 73 in the twice-daily group). The percentage of doses taken was greater with the twice-daily regimen (84.5 ± 22.8%) than with the thrice-daily regimen (72.7 ± 20.1%; P <0.001). More than 80% of the doses were taken by 72.6% and 47.3% of the patients in the two groups, respectively (P <0.001). Forty patients in the twice-daily group opened the container every 12 ± 6 h during at least 80% of the course (54.8%) while only 19.6% of the patients assigned to the thrice-daily formulation did so every 8 ± 4 h (P <0.001). The percentage of patients who opened the container a satisfactory number of times per day was significantly higher among those taking the twice-daily regimen, on days three (82.2% vs. 66.5%; P <0.05), four (76.7% vs. 51.8%; P <0.01), five (73.9 vs. 42.8%; P <0.001), six (68.5% vs. 33.7%; P <0.001), and seven (52.1% vs. 28.3%; P <0.001). Moreover, the thrice-daily group more frequently forgot to take the afternoon dose.

Conclusions: The rate of compliance with amoxicillin/clavulanic acid therapy was very low. However, compliance with the new formulation that is taken twice-daily was significantly better than compliance with the standard formulation.