ABSTRACT
This chapter discusses the possible application of ionic polymer-drug combinations as prolonged action dosage forms. Principally, ion exchange materials are insoluble ionic materials possessing acidic or basic groups, covalently bound, and placed in repeating positions on the resin chain. These charged groups are associated with other ions of opposite charge. A common procedure is to cycle repeatedly between the sodium and hydrogen forms if dealing with a cationic exchanger, or between the chloride and hydroxide forms in the case of an anion exchange resin. Ionic polymers having weak acid ionic groups are poorly soluble in gastric juice and a major release of the drug will occur in the intestines. In vitro dissolution testing is an important tool in the proper control and evaluation of drug resinate preparations. Combination of drugs with appropriate ionic polymers is a relatively simple means of altering the physicochemical and biological characteristics of drugs.
