The study demonstrated that the higher, antimicrobial dose does not provide a greater clinical benefit than the anti-inflammatory dose of 40mg, controlled release. However, the higher dose was associated with a significantly higher incidence of adverse events. Oracea is a patented, delayed release formulation of doxycycline, 40mg, which is the only FDA-approved treatment for the papules and pustules associated with rosacea.
This prospectively randomized, double-blinded, placebo-controlled clinical study enrolled 91 patients at seven investigational centers across the US. The study had two arms, and patients were treated once daily with either 100mg of doxycycline or Oracea (40mg doxycycline, controlled release). Both treatments were administered as an adjunct to topical MetroGel 1%. The treatment duration was 16 weeks, and patients were evaluated for efficacy and adverse events at baseline and at weeks four, eight, 12 and 16.
The primary endpoint was mean change in total inflammatory lesion count from baseline to the week 16 visit. Patients in the Oracea group had an average of 19.8 inflammatory lesions at baseline and experienced a decrease in lesion count of 12.5 lesions, compared with 17.7 lesions at baseline and a decrease of 12.2 lesions in the doxycycline, 100mg group. The difference between the treatment groups is neither clinically nor statistically significant (p-value = 0.83). In addition, there were no differences observed between the treatment groups regarding the secondary endpoints of Investigators Global Assessment and Clinician’s Erythema Assessment with (p-values of 0.86 and 0.50, respectively).
In contrast, a clear difference was observed between the two treatment groups in the incidence of adverse events, primarily gastrointestinal reactions. Gastrointestinal adverse events, including nausea, vomiting, diarrhea and stomach discomfort, were observed in 26% of patients administered 100mg of doxycycline versus only 5% in the Oracea group.