Ion-Exchange Resin Delivery Systems

In the continuing search for novel drug delivery systems to optimize presentation and bioavailability of established therapeutic agents, ion exchange resins should be considered as polymers with unique advantageous properties. Drugs absorbed onto ion exchange resins have been referred to as absorbates, complexes, resinates, or sometimes as salts. If the authors wish rapid dissolution in gastrointestinal tract, they may select weak cation or anionic resins, low crosslinkage, small particle size, and/or high drug potency. If maximum potency is a priority with a low molecular weight drug, they may select a resin with a high exchange capacity. It is often beneficial to begin with larger commercial particle size range and mill the complex after loading. Resin with a very fine particle-size range was used to avoid grittiness that is inherent in most ion exchange resins. The use of ion exchange resins as controlled release drug carriers in injectable products can be visualized, but practical applications will probably require a biodegradable form.