Metronidazole gel (0.75%) in Japanese patients with rosacea: A randomized, vehicle‐controlled, phase 3 study

Topical metronidazole is not currently approved in Japan as a treatment for the indication of rosacea, although 0.75% metronidazole gel was authorized in 2014 for the management of cancerous skin ulcers. We conducted a randomized, double‐blind, vehicle‐controlled study to evaluate the efficacy and safety of 0.75% metronidazole gel in Japanese patients with inflammatory lesions (papules/pustules) and erythema associated with moderate to severe rosacea. Overall, 130 patients were randomly assigned to receive 0.75% metronidazole gel (n = 65) or vehicle (n = 65), and 120 patients completed 12 weeks of treatment. The primary efficacy outcome was the proportion of patients who achieved both of the following at week 12: an improvement of >50% in the number of inflammatory lesions (papules/pustules) and a positive change of at least one degree in erythema severity. This composite outcome was achieved by 72.3% of metronidazole‐treated patients versus 36.9% of vehicle‐treated patients, with the between‐group difference demonstrating significant improvement with 0.75% metronidazole gel (p < 0.0001). All secondary efficacy endpoints (patients achieving a score of ≥3 for percent change in the number of inflammatory lesions at week 12; patients achieving a score of ≥3 for change in erythema severity at week 12; patients achieving an Investigator’s Global Assessment score of 0 or 1 at week 12; percent change over time in the number of inflammatory lesions; change over time in erythema severity) also showed improvement in the 0.75% metronidazole gel group. The incidence of adverse events was higher with metronidazole (40.0%) than with vehicle (29.2%). Of these, treatment‐related, treatment‐emergent adverse events occurred in 9.2% and 6.2% in the metronidazole and the vehicle group, respectively, but there were no new safety concerns. Overall, the results of this study have confirmed the efficacy and safety of 0.75% metronidazole gel in Japanese patients with rosacea.