Effects of some non-toxic penetration enhancers on in vitro heparin skin permeation from gel vehicles

The effects of some penetration enhancers with low toxicity such as Transcutol, propylene glycol dipelargonate (DPPG), soybean lecithin and d-limonene on the in vitro percutaneous absorption of heparin sodium salt through human skin were investigated. Using the pretreatment technique, all the enhancers tested increased heparin skin permeation with the exception of Transcutol. Measuring heparin flux from Carbopol gels containing such promoters showed that soybean lecithin, DPPG and d-limonene were able to enhance heparin skin penetration while Transcutol was not. To explain the mechanism of the effective promoters, the heparin diffusion and partitioning coefficients from the gels containing the enhancers were calculated. The results indicated that soybean lecithin and DPPG could act by increasing the heparin diffusion coefficient while d-limonene seemed to exert its enhancement effect on heparin skin/vehicle partitioning.