Percutaneous absorption of betamethasone 17 benzoate measured by radioimmunoassay

Abstract

Percutaneous absorption was studied in patients following topical application of betamethasone 17 benzoate cream and gel with occlusion by means of a sensitive and specific radioimmunoassay method. Concentrations of betamethasone 17 benzoate in plasma were between 0.3 and 5 ng/ml, indicating approximately 0.05 to 0.3% of the steroid applied to the skin was detected in plasma. Plasma betamethasone 17 benzoate levels increased in proportion to the amount of the steroid applied to the skin. High correlation between plasma betamethasone 17 benzoate levels and percent inhibition of plasma cortisol was also observed. Approximately 3 ng/ml levels of betamethasone 17 benzoate in plasma induced 90% inhibition of plasma cortisol. The data suggest that betamethasone 17 benzoate in gel base was more readily absorbed than in cream base.