title: The phototoxic and photoallergy potential of clindamycin phosphate 1.2%/ tretinoin 0.025% gel for facial acne: results of two single-center, evaluator-blinded, randomized, vehicle-controlled phase 1 studies in healthy volunteers.
abstract: BACKGROUND
  A fixed-dose combination of clindamycin phosphate 1.2% and tretinoin 0.025% gel (VELTIN® (clindamycin phosphate and tretinoin) 1.2%/0.025% Gel [VELTIN]) (clindamycin/tretinoin gel) is currently available for the once-daily topical treatment of acne.
  
  
  OBJECTIVE
  Two-phase I studies were conducted to evaluate the phototoxic and photoallergic potential of clindamycin/tretinoin gel.
  
  
  METHODS
  Study 1 (phototoxic) (n=37) and Study 2 (photoallergic) (n=58) were single-center, evaluator-blinded, randomized, vehicle-controlled, phase 1 studies conducted in healthy volunteers. In Study 1, clindamycin/tretinoin gel patches, vehicle gel patches and blank patches (no gel) were applied concurrently for 24 hours to naïve sites. After patch removal, sites were irradiated with 16 joules/cm2 of ultraviolet A light (UVA) then 0.75 minimal erythema dose (MED) of UVA/ultraviolet B light (UVB), the same irradiation protocol followed by 15 joules/cm2 of visible light (VIS), or served as non-irradiated controls. Study 2 examined the effect of repeated drug exposure and involved an induction period (6 repeat phases at the same body sites during which clindamycin/tretinoin gel and vehicle gel patches were applied for 24 hours, removed and sites irradiated with UVB +/- VIS), followed by a rest period (10 to 17 days), then a challenge period that used the protocol described for Study 1. In both studies, inflammatory responses and other cutaneous effects were evaluated at 1, 24, 48, and 72 hours after patch removal.
  
  
  RESULTS
  No subject experienced any adverse events in Study 1 (phototoxic). One subject in Study 2 (photoallergic) experienced AEs (diffuse erythema; mild application site irritation at one each of UV/VIS-irradiated clindamycin/tretinoin gel and vehicle gel patch sites) considered definitely related to study product that resulted in discontinuation from the study. Data from Study 1 and the challenge phase from Study 2 showed most subjects had no visible inflammatory reaction to clindamycin/tretinoin gel after irradiation.
  
  
  CONCLUSIONS
  Clindamycin/tretinoin gel has a favorable safety profile following UV/visible irradiation and a low potential for phototoxicity and photoallergenicity.
authors.forename: John
authors.initials: J
authors.lastname: Murray
authors.forename: Aaron
authors.initials: A
authors.lastname: Potts
mesh_terms: D000152:Acne Vulgaris / Q000150:complications* / Q000188:drug therapy; D000279:Administration, Cutaneous; D000293:Adolescent; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000009:adverse effects* / Q000627:therapeutic use; D002981:Clindamycin / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000627:therapeutic use; D017454:Dermatitis, Photoallergic / Q000209:etiology* / Q000473:pathology; D017484:Dermatitis, Phototoxic / Q000209:etiology* / Q000473:pathology; D004338:Drug Combinations; D004890:Erythema / Q000139:chemically induced / Q000473:pathology; D005260:Female; D006801:Humans; D007641:Keratolytic Agents / Q000009:adverse effects* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome; D014212:Tretinoin / Q000009:adverse effects* / Q000627:therapeutic use; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D004338:Drug Combinations; D007641:Keratolytic Agents; D002981:Clindamycin; D014212:Tretinoin; C007084:clindamycin phosphate