The stability and blanching efficacy of betamethasone-17-valerate in emulsifying ointment.
The bio-availability of betamethasone-17-valerate (Betnovate ointment) in emulsifying ointment (1 in 4 dilution) was investigated in ten subjects using a single-application vasoconstrictor assay; the blanching induced was measured using a skin reflectance spectrophotometer. The vasoconstrictor activity of the diluted preparations decreased with age. There was no significant difference between the vasoconstrictor activity of freshly made Betnovate 1 in 4 in emulsifying ointment and undiluted Betnovate ointment, and between 3-4 week old diluted Betnovate and emulsifying ointment base. Blanching induced by freshly prepared 4, 8 and 16-fold dilutions was not significantly different but a large reduction in blanching occurred on diluting 32-fold with emulsifying ointment. The degradation of betamethasone -17-valerate in emulsifying ointment was quantified by high performance liquid chromatography. More than 60% of the betamethasone -17-valerate underwent degradation within 6 h. There was a simultaneous increase in the concentration of betamethasone-21-valerate which peaked within 2 days and was followed by a slow degradation (half-life 8 days) to betamethasone free alcohol.
D001623:Betamethasone / Q000031:analogs & derivatives*; D001624:Betamethasone Valerate / Q000378:metabolism / Q000494:pharmacology*; D001682:Biological Availability; D002851:Chromatography, High Pressure Liquid; D004339:Drug Compounding; D004355:Drug Stability; D006801:Humans; D008297:Male; D009824:Ointments; D012867:Skin / Q000187:drug effects*; D013997:Time Factors
D009824:Ointments; D001623:Betamethasone; D001624:Betamethasone Valerate