ABSTRACT
Ion exchange resins have been used for many years in pharmaceutical formulations. One of the most important properties of ion exchange resins is that they contain functional groups attached to the backbone of the polymer that can exchange ions with ions in the solution. Drug delivery at the desired target via the ion exchange process occurs because of the presence of highly activated counterions at the site, resulting in the exchange of ions with subsequent drug release. Polymorphism has been a very common problem in the pharmaceutical industry. The particle size of ion exchange resins (IERs) can also be determined by microscopy, Coulter counter, and other available techniques. The porosity of dry IERs can be determined through nitrogen adsorption at –195°C, and by measuring the true density. The basic condition for loading of the drug into an ion exchange resin is that the drug, to be loaded, should be ionizable.
