Research And Application Of Coated Polymer Microneedles

As an important method for transdermal drug delivery, microneedle (MN)has been widely studied. Among different modes of MNs, coated MNs are appealing for the wide scope of active drugs. The coating layers on MNs can increase long-term stability as the active drugs are maintained in a solid state.Besides, the preparation process is simple and rapid. However, there are many problems in the fabrication process of coated MNs. Inhomogeneous drug loading, low drug loading and complex fabrication process have been the major puzzles for coated MNs. Therefore, it is urgent to address these limitations.As a kind of polymer materials with biocompatibility and biodegradability,polylactic acid (PLA) was chosen as the base material. As a kind of thickeners,polyvinyl alcohol (PVA) was a kind of biomaterials with biocompatibility and water solubility. Sucrose could maintain the stability of the drug. The main work was shown as follows:1. Using polydimethylsiloxane (PDMS) molds, solid polymer MNs made of PLA particles were fabricated using hot forming technology. The coating solutions were made of PVA, sucrose, drugs and ultra-pure water. Afterwards,mechanical property, transdermal drug delivery in vitro, drug loading and drug delivery efficiency were tested. Besides, the coating solutions were optimized.Transdermal drug delivery in vivo was conducted. All the results indicated that the drug-loaded coated polymer MNs were practical.2. Solid polymer MNs were fabricated using hot forming technology. First,PVA and sucrose were dissolved in ultra-pure water. Later, the solution was uniformly mixed with drugs. Coated MNs were fabricated using the dip-coating technology. Penetration test in vitro indicated that MNs were strong enough to pierce the skin and deliver drugs painlessly. Simultaneously, the drug delivery of the coated MN patch was greatly improved. To verify the treatment effect of MNs, insulin-coated MNs were fabricated and applied in diabetic mice. All the results demonstrated that the drug loading was increased by dipping the coating mixtures. Besides, the use of MNs was not affected.3. The coated polymer MNs were respectively fabricated using a liftable and lowerable facility, a roller, a fixture and a limit device. Afterwards, the preparation process, drug loading and transdermal drug delivery in vitro were compared. The purpose was to choose a better preparation method. All the results indicated that the fabrication process using a fixture or a limit devise was more effective and worthy of further study.