Production and evaluation of vildagliptin-loaded poly(dl-lactide) and poly(dl-lactide-glycolide) micro-/nanoparticles: Response surface methodology approach

Abstract

A laboratory scale spray dryer was used to encapsulate vildagliptin (VLG), an antihyperglycemic drug, into different polymers such as poly(dl-lactide) (PDLA), poly(dl-lactide-glycolide)-50:50 (PLGA 50:50), and poly(dl-lactide-glycolide)-75:25 (PLGA 75:25). Response surface methodology (RSM) was employed to evaluate the effects of process and formulation factors on the encapsulation efficiency (EE). The physicochemical properties of the drug-loaded micro-/nanoparticles, mainly the drug loading (DL), particle size distribution, surface morphology, drug–polymer compatibility, and release rate were investigated. % EE of drug-loaded micro-/nanoparticles were in the range of 57.10% to 76.44%. PLGA50:50 micro-/nanoparticles showed highest EE as compared to PDLA and PLGA75:25 micro-/nanoparticles. The mean particle size of the micro-/nanoparticles containing PLGA 50:50, PLGA 75:25, and PDLA polymers were 428 nm, 640 nm, and 1.22 µm, respectively. Surface morphology study revealed smooth, spherical and nonporous surface structures of the micro-/nanoparticles. Fourier transform infrared spectroscopy studies confirmed the drug–polymer compatibility. Powder X-ray diffraction analysis of micro-/nanoparticles revealed that VLG was present in the amorphous form within the micro-/nanoparticles formulations. In vitro release study demonstrated that VLG is slowly released from micro-/nanoparticles for 12 h and the drug release rate was influenced by type and viscosity of polymers used. This work suggests that PDLA, PLGA 50:50, and PLGA75:25 polymers are able to sustain the VLG release rates from micro-/nanoparticles.