Ion-exchange, an Approach to Prepare an Oral Floating Drug Delivery System for Diclofenac

Using ion-exchange resins, a multiple-unit type of oral floating dosage system has been prepared to prolong gastric emptying time of dosage form. The system is composed of beads of drug-resin complex, which are loaded with bicarbonate ions and coated with a hydrophobic polymer. The system is so designed that when the beads reach the stomach, chloride ions are exchanged with bicarbonate and drug ions. The generated CO2 is entrapped in the polymeric coated resins and causes the beads to float. In this study, Amberlite-IRA 900 was loaded with diclofenac and bicarbonate ions, using a batch method. The beads were encapsulated with a hydrophobic polymer (ethyl cellulose or Eudragit RS-100). To find an appropriate formulation, the factors affecting the drug loading, floating ability and drug release were investigated. Based on the result obtained, maximum loading efficiency was attained at 3 h, using an aqueous diclofenac solution and resin beads measuring 430 µm in diameter. Drug release from both uncoated complexes of diclofenac-resin, and diclofenac-bicarbonate-resin occurred via particle-diffusion. The ethyl cellulose-coated beads have a desirable floating capability in comparison with the Eudragit RS-100 coated beads on HCl 0.1M solution containing 0.02% polysorbate 80.