In vivo immunomodulatory, cumulative skin irritation, sensitization and effect of d-limonene on permeation of 6-mercaptopurine through transdermal drug delivery.

Using skin as a port for systemic drug administration, transdermal drug delivery has expanded greatly over the last two decades. Our aim was to formulate the single layer drug-in-adhesive transdermal patch for 6-mercaptopurine (6-MP). In vitro permeation study was carried out using modified Franz diffusion cell with and without of different concentration of d-limonene in human cadaver skin. In vivo immunomodulatory was carried out in mice, cumulative skin irritation, sensitization and patch adherence study was done in both mice and human subjects. 6-MP flux increased from 43+/-12.2 microg/cm2h (control) to 162.8+/-32.2 microg/cm2h (6% w/v d-limonene) data was significant (p<0.05), with decrease in the lag time to 35+/-9.3 min compared to control of 90 +/-15.3 min. In vivo immunomodulatory effect was shown in the Balb/c mice with 100 mumol/kg/body wt of animal for 5d (one dose/d) of d-limonene. WBC count of 13469 cells/mm peak was observed on 12th day, bone marrow cells of 26.3 x 10(6) cells/femur and alpha-esterase positive cells of 1259+/-328.4 cells/4000 bone marrow cells. Cumulative skin irritation, sensitisation and patch adherence in animals and human subjects showed no skin irritation and sensitization. Patch adhesion was greater than 90.0% respectively in both human subjects and mice. The percentage of human subjects with adhesive residue was significantly less with scores of zero. d-Limonene proved as good chemical enhancer by increasing in the skin permeability with shortened the lag time. It proved that therapeutic amount of 6-MP can be delivered through transdermal drug delivery.