Effects of topical preparations on the erythemogenicity of UVB: implications for psoriasis phototherapy.
BACKGROUND
Topical preparations are sometimes applied before phototherapy without consideration of their potential to block UVB.


OBJECTIVE
Our purpose was to examine the ability of topical preparations to block UVB.


METHODS
Volunteers pretreated with mineral oil, a clear liquid emollient, 5% crude coal tar, 6% salicylic acid ointment, emollient creams, and petrolatum underwent minimal erythema dose testing. Transmission of UVB through a clear film coated with the preparations was measured.


RESULTS
Tars and salicylic acid blocked UVB. Thick application of petrolatum and emollient creams can reduce transmission of UVB. Mineral oil and a clear liquid emollient did not significantly affect transmission or erythemogenicity of UVB.


CONCLUSIONS
Clear liquid emollient and mineral oil can be used before phototherapy. If not removed before phototherapy, preparations containing tar or salicylic acid, or thickly applied petrolatum or emollients, can block UVB and presumably reduce its efficacy in the treatment of psoriasis.
Lebwohl
M
M
Department of Dermatology, Mount Sinai School of Medicine, New York, NY.
Martinez
J
J
Weber
P
P
DeLuca
R
R
D000279:Administration, Cutaneous; D000293:Adolescent; D000328:Adult; D003033:Coal Tar / Q000494:pharmacology; D004643:Emollients / Q000494:pharmacology*; D004890:Erythema / Q000209:etiology; D006801:Humans; D008055:Lipids; D008899:Mineral Oil / Q000494:pharmacology; D009823:Ointment Bases / Q000494:pharmacology; D009824:Ointments / Q000494:pharmacology*; D010577:Petrolatum / Q000494:pharmacology; D011565:Psoriasis / Q000532:radiotherapy*; D012459:Salicylates / Q000494:pharmacology; D020156:Salicylic Acid; D014466:Ultraviolet Rays; D014467:Ultraviolet Therapy
D004643:Emollients; D008055:Lipids; D009823:Ointment Bases; D009824:Ointments; D012459:Salicylates; D003033:Coal Tar; D010577:Petrolatum; D008899:Mineral Oil; C039909:eucerin; D020156:Salicylic Acid