Metronidazole in periodontitis (IV). The effect of patient compliance on treatment parameters

Patient compliance with the unsupervised usage of prescription medication can be poor. In the treatment of periodontal infections with systemic antimicrobial agents, in situations where the efficacy of the antimicrobial agent is being evaluated, non-compliance could underestimate the true efficacy of the agent. Metronidazole is an agent with reported success in the treatment of anaerobic periodontal infections. Metronidazole is particularly effective in vitro against spirochetes, and this efficacy was investigated as a means of measuring patient compliance with metronidazole usage. Patients who had high proportions of spirochetes, i.e., > 20%, in plaques removed from diseased periodontal sites, were given metronidazole (500 mg bid) under supervision. In all individuals who received the metronidazole, there was a significant and rapid decline and/or disappearance of spirochetes from the plaque during the time interval that metronidazole was detectable in the saliva. This observed decline in spirochetes was then used to determine which patients had been compliant in a double-blind clinical trial involving the unsupervised usage of metronidazole. Only 10 of 18 patients (56%) were considered compliant in their usage of metronidazole. These 10 patients experienced a significantly greater benefit from the metronidazole than did the 8 patients who were considered noncompliant, i.e., a reduction of surgical needs of 8.3 teeth per compliant patient versus 3.6 teeth per non-compliant patient. A test for the hydrolysis of the synthetic peptide (BANA) was also able to identify most non-compliant patients. Clinical trials involving the unsupervised usage of systemic medication need to take into account patient non-compliance.