KOLOA, HAWAII — The metronidazole gel 1% approved by the Food and Drug Administration last year for the treatment of rosacea is a better product in two distinct ways than the 0.75% preparation it replaces, Dr. Guy F. Webster said at the annual Hawaii dermatology seminar sponsored by the Skin Disease Education Foundation.
The new version incorporates a higher concentration of metronidazole, of course, but it also utilizes a new water-based, alcohol-free vehicle that's much gentler on the skin of atopic dermatitis patients. Indeed, patch test studies have shown that metronidazole gel 1% (MetroGel) has a very low potential for irritation. “It's clearly beneficial as a moisturizer, let alone as an anti-inflammatory drug,” said Dr. Webster of Jefferson Medical College, Philadelphia.
The pivotal phase III clinical trial that led to FDA approval last year involved 746 rosacea patients randomized 3:1 to 10 weeks of once-daily MetroGel or its gel vehicle.
At 10 weeks, the mean inflammatory lesion count—18 lesions at baseline—was reduced by 51% in the MetroGel group and by 33% in controls.
In addition, 38% of the MetroGel group were rated by investigators' global assessment as clear or almost clear and 29% as unchanged, compared with 28% and 41%, respectively, of controls.
In a separate phase IIIb clinical trial, MetroGel significantly outperformed azelaic acid gel 15% (Finacea) in terms of tolerability. The investigator-blinded multicenter study involved 180 rosacea patients randomized to 15 weeks of once-daily MetroGel or twice-daily Finacea.
The two treatments showed equal efficacy in terms of reductions in inflammatory lesions, erythema, and physicians' global severity scores; however, only 26% of patients in the MetroGel group indicated they were bothered by stinging and burning, compared with 47% on Finacea.
Dr. Webster deemed the cost of once-daily MetroGel reasonable at slightly under $1 per day.
A potential topical therapy for rosacea worth keeping an eye on is dapsone gel 5% (Aczone), he said. It received FDA marketing approval last year for acne vulgaris, but its manufacturer, QLT Inc., has decided to delay the drug's launch until after completion of an ongoing phase IV study aimed at getting the FDA's requirement for patient blood tests removed. Meanwhile, a phase II study of Aczone for the treatment of rosacea is ongoing.
Based on Aczone's pharmacokinetics, Dr. Webster said the FDA's restriction was likely to be lifted upon presentation of additional data by QLT.
He is a consultant to Galderma, which markets MetroGel, but is not involved in the Aczone trials.
The Skin Disease Education Foundation and this news organization are wholly owned subsidiaries of Elsevier.
