EPLERENONE FLOATING MICROSPHERES: RADIOGRAPHIC AND PHARMACOKINETIC STUDIES IN RABBITS

Objective: The objective of the present investigation was to evaluate gastro-retentive performance and pharmacokinetic parameters of Eplerenone-optimized floating microspheres compared with formulated floating tablets. Methods: Microsphere contains antihypertensive drug Eplerenone as a core material encapsulated with the polymeric membrane for sustained drug release were prepared by solvent diffusion-evaporation technique. The prepared microspheres were evaluated for qualitative and quantitative parameters. The optimized formulation showed favorable in vitro floating and drug release profile. The gamma scintigraphy of the formulation was carried out in rabbit in order to determine the floating ability of the final formulation with barium sulfate. Prolonged gastric residence time of over 12 h was achieved in all the animals. Eplerenone-loaded optimized formulation was orally administered to rabbit and blood samples were used to determine pharmacokinetic parameter by using WinNonlin software 3.0 version. Results: Eplerenone floating microsphere, which are compared with pharmacokinetic parameters of the Floating tablet showed improved parameters of Cmax; similarly, time to reach peak plasma concentration (t-max) for Eplerenone Floating microspheres was 4 times increased against Floating tablet formulation. The area under the curve (AUC) for formulated floating tablet was found to be 9.69 µg/ml, whereas for floating microspheres it was 16.28 µg/ml, for formulated floated tablet absorption rate constant Ka was 1.61 h, elimination rate constant was 0.112 h and elimination half-life 6.2 h. The comparison of these data undoubtedly shows that the Cmax was not much valid, but AUC was increased to about 1.68 times in case of floating microspheres, absorption rate constant was found to be decrease 3.22 times when related to the floating microspheres, whereas Ke was found to be decrease 2.11 times when equated to floating microspheres, elimination half-life was increased by almost about two times. Conclusion: Eplerenone floating microsphere, which are compared with pharmacokinetic parameters of the floating tablets showed enhanced parameters of the formulated due to floating nature of the present designed formulation.