Preparation and Drug Release Behavior of Nifedipine-Loaded Poly(lactic acid)/Polyethylene Glycol Microcapsules

Nifedipine (NF)-loaded poly(lactic acid) (PLA) and PLA/polyethylene glycol (PLA/PEG) microcapsules are synthesized using a high-speed agitator and a syringe pump with an oil-in-water emulsion-solvent evaporation technique to evaluate the effect of PLA/PEG ratio on morphology and drug release behavior of the capsules. Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimeter (DSC), and X-ray diffraction (XRD) results indicate that PEG reacts successfully with PLA due to the ether bond between PEG and PLA. The drug release rate of PLA and PLA/PEG capsules increases dramatically from 0 to 5 min and then reaches a plateau within 15 to 20 min. Due to the high specific surface area, the amount of NF released is raised by reducing the PLA concentration from 5 wt% to 2 wt%. Unlike PLA capsules, the drug release rate of PLA/PEG capsules increases due to the size effect by varying the PLA/PEG ratio from 10/0 to 6/4. Larger PLA/PEG capsules are attributed to higher amounts of encapsulated NF. The capsules show no evidence of cytotoxicity, suggesting that the PLA and PLA/PEG drug carriers are clinically safe.