title: A double-blind evaluation of topical capsaicin in pruritic psoriasis.
abstract: BACKGROUND
  Substance P, an undecapeptide neurotransmitter, has been implicated in the pathophysiology of psoriasis and pruritus.
  
  
  OBJECTIVE
  Safety and efficacy of topical capsaicin, a potent substance P depletor, were evaluated in patients with pruritic psoriasis.
  
  
  METHODS
  Patients applied capsaicin 0.025% cream (n = 98) or vehicle (n = 99) four times a day for 6 weeks in this double-blind study. Efficacy was based on a physician's global evaluation and a combined psoriasis severity score including scaling, thickness, erythema, and pruritus.
  
  
  RESULTS
  Capsaicin-treated patients demonstrated significantly greater improvement in global evaluation (p = 0.024 after 4 weeks and p = 0.030 after 6 weeks) and in pruritus relief (p = 0.002 and p = 0.060, respectively), as well as a significantly greater reduction in combined psoriasis severity scores (p = 0.030 and p = 0.036, respectively). The most frequently reported side effect in both treatment groups was a transient burning sensation at application sites.
  
  
  CONCLUSIONS
  Topically applied capsaicin effectively treats pruritic psoriasis, a finding that supports a role for substance P in this disorder.
authors.affiliation: Department of Dermatology, University of Michigan Medical School, Ann Arbor 48109-0314.
authors.forename: C N
authors.initials: CN
authors.lastname: Ellis
authors.forename: B
authors.initials: B
authors.lastname: Berberian
authors.forename: V I
authors.initials: VI
authors.lastname: Sulica
authors.forename: W A
authors.initials: WA
authors.lastname: Dodd
authors.forename: M T
authors.initials: MT
authors.lastname: Jarratt
authors.forename: H I
authors.initials: HI
authors.lastname: Katz
authors.forename: S
authors.initials: S
authors.lastname: Prawer
authors.forename: G
authors.initials: G
authors.lastname: Krueger
authors.forename: I H
authors.initials: IH
authors.lastname: Rex
authors.forename: J E
authors.initials: JE
authors.lastname: Wolf
mesh_terms: D000287:Administration, Topical; D000293:Adolescent; D000328:Adult; D000368:Aged; D002211:Capsaicin / Q000008:administration & dosage*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011537:Pruritus / Q000188:drug therapy / Q000378:metabolism; D011565:Psoriasis / Q000188:drug therapy* / Q000378:metabolism; D013373:Substance P / Q000378:metabolism
chemical_list: D013373:Substance P; D002211:Capsaicin