Background Phenytoin (5,5 diphenylhydantoin), a widely-used anticonvulsant, has been employed both topically and systemically in the treatment of some dermatological disorders. Immunological and non-immunological defects suggests that phenytoin could be therapeutically effective for vitiligo repigmentation.
Aim of study The first objective was to evaluate the effect of phenytoin on cultures of normal human melanocytes and to assess cytotoxicity of the substance using colorimetric methods. The second objective was to select the topical product that releases phenytoin best and fastest, for further clinical studies in vitiligo patients.
Materials and methods In the first part of the study, we exposed normal human epidermal melanocyte cultures at 5,5 diphenylhydantoin at different concentrations. Melanocyte proliferation was evaluated using colorimetric assays (MTS assay), by measuring the absorbance at 490 nm with an ELISA plate reader. In the second part of the study, we formulated and obtained three types of phenytoin topical preparations: gel, hydrophilic cream, and ointment, for evaluation of the in vitro phenytoin release.
Results The statistical analysis revealed that at low concentrations (0.1, 0.5 μg/ml), phenytoin stimulates growth and cellular proliferation in melanocyte cultures. The in vitro study of drug release indicated that gel formulation gives the highest phenytoin release.
Conclusions Our result indicates that topical applications of low concentrations of phenytoin may have beneficial effects in vitiligo, which justifies its further testing on clinical trials. Our gel formulation occurred to be the most suitable for the clinical studies.