Preparation of Metformin Biodegradable Polymeric Microparticles by O/O Emulsion Solvent Evaporation: A 3² Full Factorial Design Approach

Background: Sustained release of synthetic polymeric microparticles has gained more attention as drug delivery carriers because of their properties such as good stability, low toxicity, dosing frequency, and simple and mild preparation method. The present work was envisaged to reduce the dosing frequency by preparing drug loaded biodegradable microspheres by the O/O emulsion solvent evaporation technique. Objective: The objective behind microspheres’ preparation is to sustain the metformin release by using ethyl cellulose as a synthetic polymer. The model drug metformin having a low biological half-life (1.5-3 hours) is selected. Methods: As the metformin is highly water soluble in nature, the oil-in-oil solvent evaporation techniques are used and span 80 is utilized as surfactant. The effect of stirring rate and surfactant concentration on the characteristics of encapsulation efficiency and drug release from the microsphere are investigated. Results: The results show that the drug-polymer (1:1) ratio gives better sustained release results. The obtained microparticles are characterized by X-RD analysis and Fe-SEM, and release behavior is checked for release patterns. A 3² full factorial design is employed for the responses. The free-flowing spherical microspheres show high drug entrapment efficiency. Conclusion: The data obtained suggest that microspheres can be successfully designed with sustained release for diabetic treatment.