Fabrication and evaluation for the novel ranitidine hydrochloride resinates and calculation of the kinetics and thermodynamics parameter for the ion exchange process.

Ranitidine hydrochloride (RH) resinates were prepared by bath method using a highly acidic cation-exchange resin as the carrier. The drug-resinates combination pattern was characterized by DSC and X-ray diffraction. The influences of the types of the ion-exchange resin, initial RH concentration and the reaction temperature on the process of ion exchange were investigated. Three empirical kinetics models and thermodynamics equations were studied to the ion exchange process under different temperatures. The results showed that RH combined with ion-exchange resin not simple physical mixture but by ion bond, and the rate of ion exchange increased on increasing the initial drug concentration and reducing the temperature the resin. The in vitro drug release test showed that the release process was affected by the kind of countra-ion, ionic strength and temperature. Thermodynamics results showed that the ion exchange reaction between RH and cation-exchange resin was exothermic (ΔHθr,m< <0), and the drug release process could preferably be fitted with the first order equation. In conclusion, RH resinates were prepared by the bath method with strongly acidic cation-exchange (Amberlite® IRP69) with 5 mg/mL RH solution(100mL) stirred at 298K for 1h. Drug release from resinates was fitted with Viswanathan equation, and to achieve obvious sustained-release effect, the RH-resin complex should be further coated with a semipermeable membrane.