Preparation and In Vitro /In Vivo Evaluation of Pentoxyverine Sustained Release Suspensions with a Novel Inorganic Materials as Carriers

In this study, pentoxyverine citrate sustained-release suspension was prepared, pentoxyverine citrate, Amberlite (R) IRP 69 and ethylcellulose were used as model drug, carrier and coating materia, respectively. The preparation process included drug loading, impregnating and suspension preparation. Firstly, pentoxyverine citrate drug resin composites were prepared by bath method and Ethyl cellulose was used as coating material. The binding of pentoxyverine citrate to Amberlite (R) IRP 69 was confirmed by differential scanning calorimetry (DSC) and X-ray diffraction and the results showed that the combination of pentoxyverine citrate and Amberlite (R) IRP 69 is covalently bonded rather than a simple physical adsorption. Secondly, The coated microcapsules with optimized prescription were further dispersed in a suitable suspension medium to obtain a sustained release suspension. Finally, rats were given the appropriate dose of pentoxyverine citrate sustained-release suspension and commercial pentoxyverine citrate granules, drug concentration curve after administration and the relevant pharmacokinetic parameters were studied. The in vivo pharmacokinetics test showed that the pentoxyverine citrate suspension and reference (commercial pentoxyverine citrate granules) had no significant differences for AUC(0-24h), but indicated a significant difference for t(max) and C-max. T-max of pentoxyverine citrate increased from 1 h (reference) to 2 h (test). The C-max of pentoxyverine citrate decreased from 659.134 ng/mL (reference) to 403.660 ng/mL (test), indicating a sustained release property in vivo, and the plasma concentration was relatively flat, reducing the possibility of drug side effects. The relative bioavailability of pentoxyverine citrate in sustained-release suspensions to its commercial granules was 95.09%.