Eudragit® rl100 microspheres as delayed-release system for ibuprofen: in vitro evaluation

Objective: The objective of this study was to encapsulate ibuprofen in microspheres made of Eudragit® RL100 as the polymer and evaluate it in vitro. Methods: Microspheres were prepared by the solvent evaporation method. Significant parameters in the evaluation of microencapsulation are yield, particle size, encapsulation efficiency, swelling index, uniformity factor and buoyancy. The in vitro release studies were carried out in phosphate buffer solution pH 7.4 at 37±1 ᵒC. Results: Microspheres containing higher ratio of polymer had higher yields as high as 89.25%. The external diameter ranged from 300 to 550 μ, with geometric mean close to 420 μ. Evidently, the formulation containing higher concentration of Eudragit® RL100 had a larger diameter, indicating greater cross-linking and a larger sphere, signifying a higher loading capacity. The loading efficiency was above 81%, while the swelling index was found to be between 29% to 36%, with buoyancy factor of 74.53% for the superior batch. The results suggest that ibuprofen was successfully and efficiently encapsulated. The release rates of drug-loaded microspheres are related to the amount of polymer, thus, to get extended drug release while reducing the ill effects of the drug in the stomach. In vitro release was compared with marketed product, divulging better data for the indigenously prepared samples. Conclusion: Data obtained by matching the in vitro release for the superior microspheres, so prepared and one of the commercial products showed the indigenous preparation of ibuprofen microspheres to be a better performer in the simulated gastric environment of phosphate buffer solution pH 7.4 at 37±1 ᵒC.