Dystrophic Psoriatic Fingernails Treated with 1% 5-Fluorouracil in a Nail Penetration-Enhancing Vehicle: A Double-Blind Study

Abstract

Background: Topically applied nail therapeutics need to permeate the nail plate to reach the nail bed or nail matrix and exert their potential beneficial effect at these locations to obtain a therapeutic benefit. So far only topically applied 5-fluorouracil on affected nails of psoriatic patients has been shown to produce a notable clearance. Vehicle formulations enhancing nail permeation processes are thought to increase the concentration of the active agent and therefore therapeutic efficacy, possibly enabling the use of a low concentration of the active agent thereby lowering the incidence of adverse effects. Objective: This study was designed to verify whether a recently developed nail penetration enhancer in a lotion formulation, Belanyx^® (urea, propylene glycol), improves the efficacy of a low concentration of 5-fluorouracil (1%) in psoriatic fingernail lesions. Methods: In a randomised, double-blind, left-right study the efficacy of 1% 5-fluorouracil in the Belanyx vehicle was compared to the vehicle preparation Belanyx in dystrophic fingernails of 57 psoriatic patients. Both preparations were applied in a once daily regimen for 12 weeks. Responses and adverse effects of one selected target nail were recorded at screening, at baseline and at weeks 2, 4, 8 and 12 of treatment with a final assessment at week 16: 4 weeks after the end of treatment. As parameter of efficacy was chosen the total nail area severity (NAS) score, consisting of the separate parameters nail pitting area, number of nail pits, subungual keratosis, onycholysis, oil spots and the various scores of overall improvement. Results: The efficacy of 1% 5-fluorouracil in lotion and that of the vehicle in suppressing the parameters of dystrophy were shown to be similar at the end of treatment (p = 0.063) or follow-up (p = 0.130). Both preparations produced statistically significant improvements (p ≤ 0.05) for almost all assessed parameters after 12 weeks of treatment and after the 4 weeks of follow-up. For Belanyx lotion this applied to the nail pitting area, the number of nail pits, subungual keratosis, onycholysis and oil spots. The investigators’ and patients’ opinion of overall improvement of severity as well as the total NAS score of one target nail likewise showed a statistically significant improvement at the end of treatment and at the end of the observation period (p ≤ 0.05). With the 1% 5-fluorouracil lotion the same statistically significant improvements were obtained in all of the assessed symptoms with the exception of the number of pits and onycholysis at week 12 and week 16. Possible treatment-related adverse effects were established in 6 patients showing inflammation and infection (3 patients) or discoloration (5 patients); 3 patients on 5-fluorouracil lotion showed onycholysis. Conclusion: Addition of 1% 5-fluorouracil to the nail permeation enhancer Belanyx does not increase the efficacy of the active agent in psoriatic nail dystrophy of this study population. The obtained results also suggest that Belanyx lotion can be used in this indication since it has shown a favourable efficacy-safety ratio.