In vivo comparison of the biological activity of topical methylprednisolone aceponate formulations using vasoconstriction assay

Methylprednisolone aceponate (MPA) is potent (class III) topical corticosteroid widely used for the treatment of inflammatory dermatoses. It's peculiarities are exceptionally favorable safety profile, high anti-inflammatory activity and properties of prodrug - after application to the skin MPA is transformed into active metabolite methylprednisolone 17-propionate, and this process goes more intensively in the zone of inflammation thus limiting steroid effect on intact skin. After the patent expiration generic MPA drugs which didn't pass through the full cycle of clinical trials have entered some markets, in cluding Russian. Metabolic profile of these generics and it's equivalence to the original product is unknown. Objective. To assess biological activity of various drug formulations of original (Advantan®) and generic (Komfoderm®) drugs of MPA using vasoconstriction assay in the in vivo model. Methods. Recommended doses of studied formulations were applied to the skin of laboratory animals (mini-pigs), and then experimental measurements of chromometric data were performed at specific timepoints (0.5 h, 3h, 6 h, 12 h, 24 h) using chromometer FRU WR-10 (8 mm). Results. Difference in the profile of biologic activity based on vasoconstriction assay data was noticed for all tested MPA drugs, ranging in descending order for lightness parameter L: Advantan® cream - Advantan® milk - Advantan® fatty ointment - Advantan® ointment - Komfoderm® K cream - Komfoderm® ointment - Komfoderm ® M2 ointment. Conclusions. Applicability of colorimetric method for evaluation of intensity of biologic effect of glucocorticoids based on the level of lightness of skin surface confirmed. Differences for this parameter for studied drugs detected. Noticed tendency to higher activity of the original drug in comparison to the generic.