The stability and blanching efficacy of betamethasone-17-valerate in emulsifying ointment

Abstract

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.

Drug Release and Skin Penetration from Solid Lipid Nanoparticles and a Base Cream: A Systematic Approach from a Comparison of Three Glucocorticoids

“…BM served as internal standard for PD and PC determination, whereas PD was the internal standard of BMV quantification. Since GC 21-esters can be cleaved by skin esterases [32] and GC 17-monoesters are degraded nonenzymatically [33] and may also rearrange spontaneously to the respective more stable 21-esters [34][35][36] , formulations, receptor fluid and skin were analyzed for degradation products. Prednisolone 17-ethylcarbonate (P17EC), prednisolone 21-ethylcarbonate (P21EC) and betamethasone 21-valerate (BM21V) were identified according to their retention times determined previously and quantified by relating UV absorbance (peak area) to PC or BMV, respectively.…”

Bioengineering and the patch test

“…Th1s method has been used m dermatology to assess top1cal stermd mduced blanchmg (13,14), to momtor PUVA therapy for psonasis (15) and to assess sunscreen efficacy (16). Mendelow et al (17) usmg a haematometer to assess patch tests, evaluated the haemoglobm mdex (proportiOnal to the degree of erythema) by measunng the reflectance of the skm at 566 and 640 nm.…”

The Effect of Serial Dilution of Betamethasone-17-Valerate on Blanching Potential and Chemical Stability

“…H P L C (Table 1) showed no loss of betamethasone-17-valerate from the 2-month-old (1:4, 1:16 and 1:32) and the 5-month-old (1:4) preparations. This is contrary to the rapid degradation of betamethasone-17-valerate diluted in emulsifying ointment (EO) where more than 60% label is lost within 6 h (2,4). T h e similarity of blanching responses of steroids in different dilutions could be used with advantage in the clinical situation especially when the blanching potential and clinical efficacy have been shown to be closely related.…”

“…None were tested for consistency of response to a standard preparation nor had any received any topical steroids at any time prior to the study. The sensitive, reproducible single application and modfied blanching assay of McKenzie and Stoughton (7,8,9) measured with a reflectance spectrophotometer and chemical stability determined by high performance liquid chromatography (4).…”