Determination of diphencyprone and its photo-degradation product incompounded preparations using HPLC

Diphencyprone (DPCP) is frequently used as a compounded preparation in dermatology for the treatment of alopecia and recalcitrant warts based on the immune reaction of skin allergy. However, DPCP is a non-recognized agent in Pharmacopoeia, because there are no criteria or analytical method for quality control of its powder and formulation DPCP is unstable under light irradiation because as it easily decomposes to diphenylacetylene (DPA). This study aims to develop a simultaneous HPLC analytical method for analyzing DPCP and DPA in the raw materials and compounded preparation The method required a C18 column (250 x 4.6 mm, 5 mu m) at 40 degrees C with a mobile phase of (A) 0.01 M phosphoric acid in water and (B) acetonitrile at UV 220 mm DPA conversion to DPCP in the powder and compounded preparations was accelerated after light exposure for 60 min. In addition, this resulted in different patterns depending on the wavelength of light and the formulation. That is, DPCP in compounded preparation was more unstable than that in the powder. However, the DPCP formulation in amber bottles was observed to remain stable, although the measured concentrations of DPCP were somewhat different from the nominal concentration of the compounded preparations. The control of the exact concentration is required for effective disease treatment, depending on the state of the patient In conclusion, these results will be useful for the recognition of DPCP in Pharmacopoeia and new DPCP formulation development to prevent photodecomposition.