Randomized clinical trial of metronidazole ointment versus placebo in perianal Crohn's disease

The potential for metronidazole 10 per cent ointment to exert therapeutic benefit in perianal Crohn's disease, while minimizing the adverse effects found with oral metronidazole, was evaluated in a randomized placebo-controlled study.

Subjects with perianal Crohn's disease were randomized to metronidazole 10 per cent ointment, 0.7 g applied perianally three times daily, or placebo ointment. The Perianal Crohn's Disease Activity Index (PCDAI) was scored at baseline and after 4 weeks of treatment. Perianal pain was assessed on a visual analogue scale.

Seventy-four subjects (33 metronidazole, 41 placebo) were evaluated. The mean(s.e.m.) reduction in PCDAI score at 4 weeks was 2.4(0.5) in the metronidazole group and 2.2(0.4) in the placebo group (P = 0.660). More subjects in the metronidazole group than the placebo group showed a reduction in PCDAI score of at least 5 points (10 of 27 versus 4 of 34; P = 0.031). Perianal discharge was reduced significantly in metronidazole-treated subjects (P = 0.012). A greater reduction in perianal pain was seen in the metronidazole group, which approached statistical significance (P = 0.059). No serious adverse events were reported.

Metronidazole 10 per cent ointment was not effective in the reduction of PDCAI score, but some secondary outcomes showed improvement suggestive of a treatment effect. It is well tolerated, with minimal adverse effects, and has potential as treatment for pain and discharge associated with perianal Crohn's disease.

NCT00509639 (http://www.clinicaltrials.gov).