Effects of metal or dissolving microneedles and its parameters of operation on the formation and closure of skin microchannels / 药学学报

ABSTRACT

To investigate the influence factors and effects of metal or dissolving microneedles on the formation and healing of skin microchannels, the pencil-shaped or conical stainless steel microneedles with different lengths, tip to tip space and base area, and the pencil-shaped dissolving microneedles with different tip to tip space were used. The microneedles were applied to the skin of epilatory mice and rats, and the effects of various microneedle parameters, application parameters, and animals on the microchannels were explored by the transepidermal water loss (TEWL) and methylene blue staining. Visually observe the skin local irritation caused by the microneedles. The animal experiments were approved by the Animal Experiments Welfare and Ethical Committee of Zhejiang University of Technology. The application time of the microneedle should be maintained at 30 s or more. When the insertion forces were 2, 4, 8 N, and the TEWL initial values of the formed microchannels were 12.9, 33.0, 40.4 g·m-2·h-1, respectively. When the length of metal microneedle were 400, 600, 800 μm, and the TEWL initial values of the formed microchannels were 37.1, 40.4, 49.5 g·m-2·h-1, respectively. When the tip to tip space of metal microneedle were 400, 600, 800 μm, and the TEWL initial values of the formed microchannels were 33.2, 40.4, 55.8 g·m-2·h-1, respectively. When the base area of metal microneedle were 0.16, 0.35, 0.62 cm2, and the TEWL initial values of the formed microchannels were 35.1, 40.4, 67.1 g·m-2·h-1, respectively. The effects of conical and pencil-shaped microneedles are similar. When the tip to tip space of pencil shaped dissolving microneedle were 400, 600, 800 μm, and the TEWL initial values of the formed microchannels were 49.8, 60.5, 70.5 g·m-2·h-1, respectively. The TEWL baseline values of animal skins of different genders and series are different, but the tendency of microchannels formation and closure is similar. Visual inspection revealed that the slight erythema caused by the microneedles subsided within 24 h. Microneedles of different parameters have different effects on microchannels. The microchannels closed within 24 or 48 h, and the skin local irritation caused by microneedle was mild.