Magnesium ascorbyl phosphate loaded in dissolving stiff microneedles containing cellulose nanofiber

초록

Magnesium ascorbyl phosphate (MAP) was loaded in a dissolving microneedles (MNs) composed of cellulose nanofiber (CNF), hyaluronic acid, collagen, and trehalose for its effective dermal delivery. MN matrices whose MAP content was 7.5, 14, and 24.5% were fabricated by casting mixture solutions containing MAP on silicone molds, centrifuging and drying them at room temperature. On the SEM micrographs of MN matrices, a 15 & times; 15 array of pyramidal needles (300 mu m in base width and 600 mu m in height) were observed and the polymeric needles were close to the pyramidal holes of the mold and the metallic needles of a master in terms of the shape and the dimension. The stiffness of the needles markedly increased with little decrease in failure load when MAP was included in the MN matrix as low as 7.5%. The stiffness of the needle appreciably decreased with a small decrease in failure load at a higher MAP content (e.g. 14 and 24.5%). Even though the high inclusion of MAP in the MN matrices (e.g. 14 and 24.5%) deteriorated the stiffness of needles, the stiffness was sufficient for skin perforation regardless of MAP content. The cumulative amount of MAP permeated though skin was proportional to the MAP content of a microneedle matrix. Not only the needles but also the base of a MN matrix seemed to act as a depot for the skin permeation of MAP, leading to a long-lasting permeation. A high content of MAP was unfavorable in terms of in vitro cellular toxicity. Regardless of MAP content, no severe toxicity was observed if the concentration of the constituents of the MN matrices was kept below 100 mu l/ml.

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