Modified microneedle roller enhancing percutaneous absorption of triamcinolone acetonide by human hyperplastic scar skin

Objective To evaluate the role of modified microneedle roller in promoting permeation of triamcinolone acetonide across human hyperplastic scar skin.Methods The morphology of human hyperplastic scar skin was visualized by methylene blue staining and H-E staining after the insertion by microneedles of different lengths.The content of triamcinolone acetonide was determined by high performance liquid chromatography(HPLC).The in vivo absorption characteristics across human hyperplastic scar skin were investigated by elution method and the homogenization method at 1hand 12 hafter drug application.Skin irritation was assessed by transepidermal water-loss(TEWL)measurement and laser Doppler flowmetry.Results The preferred microneedle length of 500μm effectively penetrated through the stratum corneum,and the distribution of the microchannels was homogeneous.It was found that 27.42% and 60.64% of the drug administered entered the skin at 1h and 12 h,respectively.The drug accumulation in the skin at 12 hdecreased to 45.98% of that at 1hafter intracutaneous injection,while the accumulation increased to 2.73-fold and 4.18-fold in the microneedle group and direct application of triamcinolone acetonide cream group,respectively,with the content of microneedle group being 3.56-fold that of the direct cream application group(P0.05).Triamcinolone acetonide distribution was not homogeneous at 12 hafter intracutaneous injection,with the level being(4.83±5.51)μg,while the distribution in the microneedle group was homogenous,with the level being(0.93±0.14)μg.TEWL results showed no significant difference in skin irritation between microneedle and intracutaneous injection group;however,laser Doppler flowmetry showed that the skin irritation of intracutaneous injection group was 8.40-fold that of microneedle treatment group.Conclusion Modified microneedle roller treatment followed by cream application,compared with intracutaneous injection,can yield more homogeneous distribution and less skin irritation in human hyperplastic scar skin,but its efficacy for scar treatment remains to be further verified.