A randomized, double-blind, placebo-controlled trial of the combined effect of doxycycline hyclate 20-mg tablets and metronidazole 0.75% topical lotion in the treatment of rosacea

Abstract

Subantimicrobial doses of doxycycline may improve outcomes in rosacea when combined with topical metronidazole and used as maintenance monotherapy. The purpose of this study was to evaluate the safety and efficacy of doxycycline hyclate 20 mg (subantimicrobial dose doxycycline) administered twice daily as an adjunct to metronidazole 0.75% topical lotion in the treatment of rosacea. Patients received subantimicrobial doses of doxycycline twice daily plus metronidazole (n = 20) or placebo plus metronidazole (n = 20) for 12 weeks. Subantimicrobial-dose doxycycline or placebo monotherapy continued for 4 weeks. The primary efficacy measure was change from baseline in total inflammatory lesions at weeks 2 and 16. Total inflammatory lesions were reduced significantly (P =.048) by week 4 and by all subsequent visits in the subantimicrobial-dose doxycycline/metronidazole group compared with placebo/metronidazole. Changes from baseline increased over time and were maintained during subantimicrobial-dose doxycycline monotherapy. Adjunctive use of subantimicrobial dose doxycycline significantly reduced the clinical signs of rosacea compared with metronidazole alone and may be useful maintenance monotherapy.