Metronidazole in the treatment of rosacea: do formulation, dosing, and concentration matter?

BACKGROUND: Topical metronidazole is commonly used in the management of rosacea. No consensus on the optimal formulation, concentration, or dosing regimen exists. PURPOSE: To assess the relative efficacy of metronidazole cream, gel, and lotion at concentrations of 0.75% and 1%, in dosing regimens of once and twice daily. METHODS: A meta-analysis of published metronidazole efficacy rates was performed. RESULTS: In non-weighted analysis, the mean efficacy was 28.2% (95% confidence interval [CI], 22.0%-34.4%) for the cream, 38.4% (95% CI, 18.4%-58.4%) for the gel, and 35% for the lotion. Confidence intervals for QD versus BID dosing and 0.75% versus 1% concentrations also overlapped. In weighted analysis, the mean reduction was 31.3% for the cream, 22.1% for the gel, and 35% for the lotion. CONCLUSIONS: Metronidazole cream, gel, and lotion vehicles have similar efficacies. There were no substantial differences between concentrations of 0.75% and 1%, or between once daily and twice daily regimens.