Penetration and distribution of thiocolchicoside through human skin: comparison between a commercial foam (Miotens) and a drug solution

Penetration and distribution of thiocolchicoside from a commercially available foam (Miotens 0.25%, w/v) through human excised full-thickness skin were evaluated using two different in vitro apparatus: a Franz diffusion cell and a Saarbruecken penetration model-based cell. In order to evaluate the intrinsic capability of the drug to penetrate into the skin, a simple drug aqueous solution prepared at the same drug concentration as Miotens was also tested. Results showed that both apparatus were suitable to study thiocolchicoside penetration into human skin. Penetrated drug amounts were comparable using the two apparatus, probably because skin acts as "sink" for the drug. Miotens was found to significantly promote thiocolchicoside accumulation into full human skin thickness in comparison with the simple drug solution. The mixture of propylene glycol and propylene glycol diperlargonate contained into Miotens foam has been proven to be effective to promote penetration of thiocolchicoside into human skin.