The Relevance of Salicylic Acid in the Treatment of Plaque Psoriasis with Dithranol Creams

Abstract

The relevance of salicylic acid in dithranol creams was evaluated in a double-blind study. Patients with chronic plaque psoriasis were treated using a short-contact schedule for dithranol on an outpatient basis. A left-right comparison was carried out between sites treated with either dithranol with 2 % salicylic acid (D+S) or dithranol in the same base without salicylic acid (D-S). Clinical results were evaluated once a week using the psoriasis area severity index. In order to quantify the improvement, flow cytometric measurements were done using the monoclonal antibody K_s8.12, recognizing keratin 16 in normal and lesional epidermis. Simultaneously, relative DNA content was quantified which previously was described as a useful method to monitor a therapeutic effect. Both PASI scores and K_s8.12 binding decreased after 6 weeks treatment with D+S and D-S. However, percentages of cells in SG₂M phases did not show a significant change. No significant difference was observed between sites treated with either D+S or D-S. Therefore we conclude that the addition of salicylic acid in a concentration of 2 % does not enhance the efficacy of dithranol creams and we confirm that K_s8.12 is a useful quantitative marker for therapeutic efficacy.

Skin Irritation by Dithranol Cream: A Blind Study to Assess the Role of the Cream Formulation

“…Our assay supports the assertion that salicylic acid by itself is not pro-in£ammatory (cream 8) (6,23,24). Not much is known about the e¡ect of salicylic acid on the clinical e¤cacy of dithranol therapy.…”

“…This implies that the irritation we saw was caused by a higher skin concentration of dithranol. On the other hand not all authors con¢rm an enhanced skin penetration by salicylic acid (24,26). It might be that the salicylic acid in£uences the dithranol irritation itself by a so far unknown mechanism, without in£uencing the penetration of dithranol.…”

Combinations of classical time‐honoured topicals in plaque psoriasis: a systematic review

“…Twelve papers were found on the combination of penetration enhancers and topical treatments other than corticosteroids 15–26 . Seven papers were excluded because they were on the combination with dithranol 15–21 …”

S3 – Guidelines on the treatment of psoriasis vulgaris Update 2011

“…In a study by de Mare et al (EG B), only 10 % of patients reported skin irritation [98]. In a study by de Mare et al (EG B), only 10 % of patients reported skin irritation [98].…”

“…For dithranol monotherapy, there was one grade A 2 study [96], 11 grade B studies [97][98][99][100][101][102][103][104][105][106][107], and 1 grade C study [108]. For dithranol monotherapy, there was one grade A 2 study [96], 11 grade B studies [97][98][99][100][101][102][103][104][105][106][107], and 1 grade C study [108].…”