Purpose: The use of biodegradable polymers has been prominent in the field of drug delivery due to its degradability and biocompatible properties. These polymers break down in the body and produce non-toxic natural by-products which are easily eliminated. On the same line biodegradable microneedles have been researched and have several benefits as compared to other types of microneedles. Biodegradable microneedles on insertion into skin produce non-sharp waste and can be engineered in a way to allow a rapid or slow release of drug. In this study PLGA (poly (D, L-lactic co-glycolic acid)) microneedles (MN) were fabricated and characterized for its controlled release profile using FITC-Dextran as a model drug for higher molecular weight (MW) molecule (40KDa) as well as for visualization purposes.
Methods: For the fabrication of PLGA microneedles, two grades of PLGA were chosen; 1) PLGA (50:50), MW being 75 kDa and 2) PLGA (65:35) with MW being 45-75 kDa. Briefly, the polymer was dissolved in acetonitrile, and drug was dispersed until a uniform clear solution was seen. The microneedles were fabricated using mold casting technique and left to dry overnight. Microneedles were characterized using electron microscopy for height, width and base. Microneedles were subjected to an In Vitro Release test to account for its controlled release profile. Microneedles were attached to a glass vial containing phosphate buffer saline. Samples were collected at definite time intervals of 0 h, 2 h, 4 h, 8 h, 12 h ,24 h, 36 h, 48 h, 60 h, 72 h, 96 h, 120 h, 144 h and 168 h.
Results: FITC-Dextran loaded PLGA microneedles were successfully fabricated using mold casting technique. The microneedles had a dimension of 410 µm height, 257 µm width of base and 25 µm width of tip of MN. The in vitro release profile of the microneedles was biphasic; initial burst release was seen in the initial 2 h period after which the release became gradual with time. Microneedles prepared with PLGA (65:35) showed an initial burst release of 49.56 % after which the release became steady with a 10% increase in the next 72 h. Similarly in the case of PLGA (50:50) , the initial burst release was fond to be 54.78% after which the release became gradual with 73.24 % drug release by 72h he release pattern by both the PLGA grades was in accordance to the fact that a higher glycolic acid proportion exhibits a faster release rate.
Conclusion: Biodegradable PLGA microneedles with FITC-Dextran as model molecule were successfully fabricated using mold casting technique. Microneedles owing to is shape and polymer matrix composition followed different release profiles. Drug release from microneedles prepared using PLGA (50:50) showed a faster release profile as compared to the microneedles prepared with PLGA (65:35) due to a higher glycolic acid concentration. The overall results predicted the mechanism involved and different application of PLGA microneedles based on release kinetics.
Narasimha Murthy– Professor-Pharmaceutics and Drug Delivery, University of Mississippi, University, Mississippi