Benefits of metronidazole gel for rosacea treatment

August 1, 2006

National report - Results of a phase 3B study comparing once daily treatment with the new 1 percent metronidazole gel (MetroGel, Galderma) and twice daily application of 15 percent azelaic acid gel (Finacea, Intendis) demonstrate that the two products have statistically similar efficacy, safety and tolerability in the treatment of moderate papulopustular acne, says John E. Wolf, Jr., M.D., professor and chairman, department of dermatology, Baylor College of Medicine, Houston.

The trial was designed to establish the noninferiority of metronidazole 1 percent gel to the azelaic acid product. It was a 15-week, multicenter, investigator-blinded study that enrolled 160 patients at 15 sites and randomized them 1:1 to the two treatment groups. Follow-up visits were conducted every three weeks.

Less as good as more

At study completion, the median reduction was 80 percent for the metronidazole group and 77 percent in azelaic acid-treated patients. The two topical medications also performed similarly throughout the study in improving investigator's global severity scores and erythema severity scores.

Safety assessments included severity ratings of dryness, scaling, itching and stinging/burning. On average, both products caused only mild adverse events, and with a few exceptions, there were generally no differences between the treatments for any of these local reactions. The patients' self-assessments revealed some statistically significant and numerical differences between products favoring metronidazole gel with respect to tolerability and satisfaction measures. However, the marked clinical improvement achieved with both products translated into benefits for improving quality of life.

"Metronidazole and azelaic acid are the mainstays of topical therapy for rosacea, and so this randomized, parallel comparison study provides important information to treating physicians." Dr. Wolf says.

"However, it is also important to note that metronidazole achieved its benefits with just once daily use. That is a big step forward in improving treatment convenience, and it might be expected to result in better patient compliance as well as possible cost savings for the metronidazole product compared with twice daily azelaic acid gel."

Benefits of new formulation

The 1.0 percent metronidazole gel tested in the current study contains a higher concentration of active ingredient in a novel vehicle, which not only allows greater solubilization of metronidazole, but also improves drug delivery, is cosmetically pleasing and hydrates the skin without causing significant irritation.

The vehicle is a 92 percent water-based gel and contains HSA3 that consists of three ingredients - niacinamide, beta cyclodextin and a low concentration of propylene glycol.

To be eligible for participation in the phase 3B study, patients had to be at least 18 years old, have an investigator's global severity score of three on a zero-to-four scale, eight to 50 facial inflammatory lesions and no more than two nodules. The enrolled population had a mean age of 51 years (range, 31-78) and was predominantly female (73 percent) and Caucasian (86 percent) with skin types II (40 percent) or III (31 percent).

Both treatments had a relatively rapid onset of efficacy for reducing inflammatory lesions. At study conclusion, the proportions of patients considered successes according to the global severity and erythema severity scores rose to about 55 percent and 42 percent, respectively, in both groups.

Results of the safety analyses showed that for all signs and symptoms assessed, mean severity scores were "mild" in both groups. However, a few significant differences were noted. For the assessment of stinging and burning, the mean severity score at three weeks was significantly worse in the azelaic acid group compared with the metronidazole-treated patients, and azelaic acid was also associated with a significantly higher "worst" score. The mean scaling severity score was significantly worse in the metronidazole group at six weeks and the mean worst score was also higher among patients using metronidazole.