STUDIES ON STABILITY OF 2,3-DIPHENYLCYCLOPROPENONE IN CONTACT WITH WATER AND AQUEOUS NaCI SOLUTIONS. CONCLUSIONS FOR PURPOSE OF TOPICAL THERAPY OF PATIENTS WITH ALOPECIA AREATA.

Diphenylcyclopropenone (DCP) is a topically administered agent used for more than three decades for treatment of alopecia areata (AA). Moreover, numerous recent studies show it's efficiency in treatment of cutaneous metastatic melanoma. Despite being a potentially useful drug still very little is known about the pharmacokinetics of DCP. The authors investigated the stability of DCP solutions in propylene glycol with the addi- tion of 0.9% aquous solution of natrium chloride (0.9% NaCI) or with water. DCP was prepared in two concentrations: 0.1% and 3%. It's stability was then measured with different proportions of 0.9% NaCI or water added and in different temperatures. Contrary to common opinion that DCP solutions are extremely unstable, authors have found them to be relatively stable. DCP solutions with the addition of equal quantity of 0.9% NaCl decomposed slowly at the temperature of 37C but after 70 h all solutions still contained more than 80% of initial DCP. Solutions of DCP with the addition of 1% of water at the temperature of 4'C are in the present study stable, containing more than 98% of initial DCP after 20 days. Authors discuss the results in spite of possible metabolism of DCP on the surface of human skin during topical immunotherapy.