title: Re-examining crude coal tar treatment for psoriasis.
abstract: Two separate, double-blind, randomized, half-and-half body comparisons, each involving 20 in-patients with psoriasis, were conducted to compare the effect of different concentrations of crude coal tar in yellow soft paraffin. The therapeutic effect of 1% crude coal tar used twice daily for 10 days was significantly less than that achieved with an incremental regimen starting at 5% and increasing by 5% every second day to a maximum of 25%. No such difference was seen when a steady concentration of 5% was compared with the same incremental regimen. We conclude that there appears to be no benefit from exceeding a concentration of 5% crude coal tar in yellow soft paraffin in the treatment of patients with psoriasis and that the plateau in the dose-response curve for the action of crude coal tar in psoriasis begins at a point between 1 and 5%.
authors.affiliation: Department of Dermatology, University of Glasgow, U.K.
authors.forename: R E
authors.initials: RE
authors.lastname: Williams
authors.forename: D M
authors.initials: DM
authors.lastname: Tillman
authors.forename: S I
authors.initials: SI
authors.lastname: White
authors.forename: E L
authors.initials: EL
authors.lastname: Barnett
authors.forename: R M
authors.initials: RM
authors.lastname: Mackie
mesh_terms: D000287:Administration, Topical; D000328:Adult; D000368:Aged; D003033:Coal Tar / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011565:Psoriasis / Q000188:drug therapy*
chemical_list: D003033:Coal Tar