Preparation, Characterization and Evaluation of Drug Release Properties of Simvastatin-loaded PLGA Microspheres

Abstract Microspheres formulated from poly (D, L-lactic-co-glycolide) (PLGA), a biodegradable polymer, have been extensively evaluated as a drug delivery system. In this study, the preparation, characterization and drug release properties of the PLGA microspheres were evaluated. Simvastatin (SIM)-loaded PLGA microspheres were prepared by oil-in-water emulsion/solvent evaporation method. The microspheres were then frozen to −80 °C, they were freeze dried for 24 h. Characterization of SIM-loaded PLGA microspheres was evaluated by X-ray diffraction analysis, Fourier transform infrared spectroscopy analysis, and scanning electron microscopy (SEM). Drug release potential was evaluated by UV-spectrophotometry. The experimental results revealed that SIM-loaded PLGA microspheres can be successfully obtained through solvent evaporation method with appropriate morphologic characteristics and high encapsulation efficiency. The drug release pattern from polymeric microspheres in the phosphate buffered saline medium was measured during a 21-day period using UV-spectrophotometry. The correlation coefficient value (r 2 = 0.9878) of the trend lines of the graph showed that the SIM-loaded PLGA microspheres best fit with zero order release pattern. No burst release was observed with polymeric matrix. The drug release characteristic of the microspheres ascertained that the release was about 27% for SIM-loaded microspheres, which occurred within the first 6 days after maintaining the microspheres in phosphate buffer saline. Also, the microspheres successfully presented a slow release and the duration of the release lasted for more than 21 days. It can be concluded that SIM-loaded PLGA microspheres hold great promise for using as a drug-delivery system in biomedical applications, especially in drug delivery systems and tissue engineering

Assessment of the imprinting efficiency of an imide with a “stoichiometric” pyridine-based functional monomer in precipitation polymerisation

The efficiency of the stoichiometric non-covalent imprinting of the imide 2,3,5-tri-O-acetyluridine (TAU) with 2,6-bis(acrylamido)pyridine (BAAPy) as functional monomer due to their strong donor-acceptor-donor/acceptor-donor-acceptor (DAD/ADA) hydrogen bond array interaction has been evaluated by bulk imprinting. This study is the first to investigate the imprinting and template rebinding efficiencies of the TAU/BAAPy molecularly imprinted polymeric (MIP) system prepared by precipitation polymerisation. We found that the stoichiometric 1:1 T:FM ratio has not been maintained in precipitation polymerisation and an optimal TAU:BAAPy ratio of 1:2.5 was obtained in acetonitrile without agitation affording an affinity constant (1.7 × 104 M?1) and a binding capacity (3.69 ?mol/g) higher than its bulk counterpart. Molecular modelling, NMR studies, and selectivity assays against analogues uridine and 2,3,5-tri-O-acetyl cytidine (TAC) indicate that, aside from the DAD/ADA hydrogen bond interaction, BAAPy also interacts with the acetyl groups of TAU. Template incorporation and rebinding in precipitation MIPs are favoured by a moderate initiator concentration, ie, initiator:total monomer (I:TM) ratio of 1:131, while low I:TM ratio (ie, 1:200) drastically reduced template incorporation and binding capacity. Vigorous agitation by stirring showed higher template incorporation but significantly lower template rebinding compared to that prepared without agitation. While the imprinting efficiencies for the best performing bulk and precipitation TAU MIPs generated in this study were moderate, 41% and 60%, respectively, their rebinding capacities were only between 3 and 4% of the incorporated template. We also present quantitative nuclear magnetic resonance spectroscopy as an efficient method for MIP characterisation

Encapsulation of irinotecan in polymeric nanoparticles: Characterization, release kinetic and cytotoxicity evaluation

Objective(s): Irinotecan is a potent anti-cancer drug from camptothecin group which inhibits topoisomerase I. Recently, biodegradable and biocompatible polymers such as poly lactide-co-glycolides (PLGA) have been considered for the preparation of nanoparticles (NPs). Materials and Methods: In this study, irinotecan loaded PLGA NPs were fabricated by an emulsification/solvent diffusion method to improve the efficacy of irinotecan. The effect of several parameters on the NPs’ characteristics was assessed, including the amount of drug and polymer, the amount and volume of the poly vinyl alcohol as a surfactant, and also the internal-phase volume/composition. The irinotecan entrapment efficiency and the particle size distribution were optimized by changing these variables. The cytotoxicity of the particles was evaluated by cell viability assay.Results: NPs were spherical with a comparatively mono-dispersed size distribution and negative zeta potential. Selected formulation (S9) showed suitable size distribution about120 nm with relative high drug entrapment. MTT assay showed a stronger cytotoxicity of S9 against HT-29 cancer cells than control NPs and irinotecan free drug. The release kinetic indicated Log-Probability model in S9.Conclusion: Our results demonstrated that the designed NPs show suitable characteristic and also great potential for further in vivo cancer evaluation