In vitro skin penetration of griseofulvin in rat and human skin from an ointment dosage form

Penetration and permeation of griseofulvin into and across the rat skin after application of three ointment formulations containing either dimethylacetamide (DMAC) or diethylene glycol monoethylether (DGME) or the ointment base alone (control--without DMAC or DGME) were studied, in vitro. Penetration and permeation of griseofulvin into and across the human skin after application of DGME ointment was also studied. Permeation of griseofulvin across the rat skin was highest for the DMAC ointment, followed by the DGME ointment and lowest for the control. Concentration of griseofulvin in the upper layers of the skin (i.e., surface to 100 micron depth) was also highest for DMAC and lowest for the control. However, the skin levels from the DGME ointment could not be distinguished (statistically) from the other two formulations. In comparison to rat skin, human skin is much less permeable. Amount of griseofulvin (from DGME ointment) that permeated through the rat skin was 14 times the amount that permeated through the human skin. Concentration of griseofulvin in the upper layers of the rat skin were 4 times the concentration of the drug in the upper layers of the human skin. The concentration of griseofulvin in the various layers of the human skin after one topical application were far greater than those reported after prolonged peroral administration.