Ion-exchange, an approach to prepare an oral floating drug delivery system for diclofenac

ABSTRACT

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 CO[2] 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 m 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 HC1 0.1M solution containing 0.02% polysorbate 80