Investigation of Drug Polymer Compatibility: Formulation and Characterization of Metronidazole Microspheres for Colonic Delivery

For the design and development of any novel formulation, assessment of compatibility of drug with excipients by different techniques such as thermal and isothermal stress testing are recommended. During pre-formulation studies common methods like UV-Spectrophotometric methods, FTIR are used for the study of compatibility. In the present investigation drug-excepient compatibility study of was conducted for metronidazole with ethyl cellulose to formulate microspheres by using different ratio of drug: polymer for colonic delivery. The drug and polymer mixtures were stored at 50 °C for 2 weeks. The samples were then characterized using UV Spectrophotometric method, FTIR. The results show that metronidazole was compatible with ethyl cellulose; hence ethyl cellulose can be used for formulation of metronidazole microspheres. Microspheres were prepared by modified Novel Quasiemulsification solvent-diffusion method to study the effect of ethyl cellulose on drug release with different proportions of metronidazole and ethyl cellulose. Prepared microspheres of ethyl cellulose were evaluated for size, morphology, sphericity study, percentage yield, loose surface crystal study, drug content and entrapment efficiency. In vitro drug release study was conducted by buffer change method to mimic Gastro Intestinal environment. The investigations revealed that microspheres prepared with metronidazole: ethyl cellulose ratio (1:2) show only 19.394 ±0.67% drug release in first 5 hours and 46.72 ±0.69% in 12 hours, which prove the potentiality of ethyl cellulose for colonic delivery of drugs.