Background: Doxycycline calcium (WC2055) is a drug substance with a possible role in the treatment of acne. The objective of this study was to evaluate the safety and efficacy of three doses of doxycycline calcium tablets compared with placebo in the treatment of moderate to severe inflammatory facial acne vulgaris.
Methods: This was a randomized, double-blind, phase 2 dose-ranging study in subjects with moderate to severe inflammatory acne aged 12 years to 45 years. Subjects were randomized to receive doxycycline calcium tablets 0.6, 1.2, or 2.4 mg/kg/day or placebo, and instructed to take their tablets once daily for 12 weeks, in the evening at least 1 hour before or 2 hours after mealtime. The primary efficacy variables were the dichotomized Investigator's Global Assessment score (success or failure) at week 12 (success defined as ≥ 2 score decrease from baseline) and the absolute change from baseline to week 12 in inflammatory lesion count.
Results: A dose-response effect was seen with doxycycline calcium formulation in subjects with moderate to severe inflammatory acne. The highest dose-group (corresponding to approximately 2.4 mg/kg/day) showed a statistically significant difference from placebo. The dose-response effect was confirmed by logistic regression analysis for both treatment success and incidence of gastrointestinal adverse events. A limitation of this study is that safety and efficacy were only studied on moderate to severe inflammatory acne. Also, the study was not prospectively powered to show efficacy differences.
Conclusion: Doxycycline calcium shows a dose-response effect in reducing inflammatory lesions in subjects with moderate to severe inflammatory acne.