title: The combination formulation of clindamycin 1% plus benzoyl peroxide 5% versus 3 different formulations of topical clindamycin alone in the reduction of Propionibacterium acnes. An in vivo comparative study.
abstract: BACKGROUND
  Isolates of Propionibacterium acnes resistant to one or more anti-acne antibiotics (most commonly erythromycin) are being increasingly reported, and the emergence of resistant strains can be associated with therapeutic failure of topical treatment.
  
  
  OBJECTIVE
  Comparison of the in vivo effectiveness of the combination of clindamycin 1% plus benzoyl peroxide 5% in a gel formulation to that of each of 3 clindamycin 1% preparations (gel, lotion, and solution) with respect to reduction in counts of P. acnes cultured from the foreheads of healthy volunteers.
  
  
  METHODS
  The effects of treatment with the 4 study drugs were compared in an open-label study. Cultures were collected before, after 1 week and after 2 weeks of treatment.
  
  
  RESULTS
  Treatment with the combination formulation resulted in a 99.8% (> 2 logs) reduction in total propionibacterial numbers after 1 week of therapy compared with 30 to 62% (< 1 log) decreases for the different formulations of topical clindamycin alone. By the end of week 2, the combination had decreased P. acnes counts by more than 99.9% (> 3 logs) relative to reductions of from 88 to 95% (< or > 1 log) for the single agent formulations.
  
  
  CONCLUSIONS
  Under the conditions of the present study, the combination of clindamycin 1% plus benzoyl peroxide 5% gel produced more rapid and highly significant reductions in P. acnes compared with formulations containing clindamycin alone.
authors.affiliation: Department of Dermatology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA.
authors.forename: J
authors.initials: J
authors.lastname: Leyden
authors.forename: K
authors.initials: K
authors.lastname: Kaidbey
authors.forename: S F
authors.initials: SF
authors.lastname: Levy
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology*; D001585:Benzoyl Peroxide / Q000494:pharmacology*; D002981:Clindamycin / Q000008:administration & dosage / Q000494:pharmacology*; D015169:Colony Count, Microbial; D003627:Data Interpretation, Statistical; D004338:Drug Combinations; D005260:Female; D005546:Forehead / Q000382:microbiology; D005782:Gels; D006801:Humans; D008297:Male; D008875:Middle Aged; D009824:Ointments; D011425:Propionibacterium acnes / Q000187:drug effects* / Q000302:isolation & purification; D012867:Skin / Q000382:microbiology; D012996:Solutions; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents; D004338:Drug Combinations; D005782:Gels; D009824:Ointments; D012996:Solutions; D002981:Clindamycin; D001585:Benzoyl Peroxide