The influence of anti-irritants on captopril hydrophilic gel

In this study, we compared the irritation inhibition of various types of anti-irritants such as antihistamines (cyprohetadine, diphenhydramine, and promethazine), alpha-hydroxy acids (gluconolactone and gluco-delta-lactone), corticosteroids (betamethasone and clobetasol), and ion channel modulating agents (amiloride, ethacrynic acid, nifedipine, and verapamil) on the adverse dermatological reaction caused by captopril gel using noninvasive bioengineering methods including measuring the transepidermal water loss (TEWL) and the color change of skin surface [such as change chroma (delta C) and difference in color (delta E) between the gel-treated site and the untreated site]. In addition, the influence of these anti-irritants on the penetration capacity of captopril through the rabbit skin was also investigated. The results showed that the TEWL, change chroma (delta C), and difference in color (delta E) of skin were significantly reduced via incorporating diphenhydramine and clobetasol, indicating that both substances had potent irritation inhibition activity. Moreover, these substances had no effect on the percutaneous absorption of captopril gel. However, flux of the captopril with anti-irritants was about 480 microg/cm2/h and the required minimum administration area to obtain the minimum effective concentration was about 15 cm2, indicating that this formulation could possibly be developed for a transdermal drug delivery system.