Development of Cinnarizine Microballoons by Sequential Optimization and In Vivo Imaging by Gamma Scintigraphy

Background: The drug cinnarizine is used in the treatment of vertigo and migraine. The main drawback is its very low water solubility which causes unpredictable bioavailability. Solubility is better in acidic pH. Therefore, gastro-retentive formulation would be beneficial to improve the bioavailability of the drug. Objective: The objective of the study was to prepare floating microballoons of cinnarizine which would float in the gastric fluid and release the drug in a sustained manner. Methods: Microballoons were prepared by diffusion solvent evaporation technique using polymers (Eudragit® S100, Eudragit® RLPO, Eudragit RL®100), characterised by FTIR, XRD, DSC and optimized by sequential simplex design. For optimization, formulations were graded with respect to formulation efficiency (percentages of yield, sphericity and drug content) and performance index (buoyancy and dissolution efficiency), from which the overall response of the formulations was determined. Finally, the optimized formulation was radiolabelled with 99mTc-MIBI and fed to Wistar albino rats and was evaluated for gastric retention by gamma scintigraphic study. Results: FTIR studies indicated drug and polymers were compatible. DSC and XRD analysis confirmed that the drug was in amorphous state in the formulation. SEM studies confirmed the sphericity of the microballoons. Formulation N7 showed the best overall response (65.61) which was the nearest to the target. Gamma scintigraphic study confirmed that the formulation was retained in the stomach for more than 5 h. Conclusion: The results indicated that floating microballoons of cinnarizine would stay in the stomach for prolonged period and thereby improve the bioavailability of the drug.