An ion-exchange resin (IER) comprises an insoluble, commonly synthetic matrix possessing ionizable groups capable of exchanging ions with those in bulk solution with which it is in contact. Thus, under appropriate conditions it can deliver to or sequester chemical species from an aqueous environment. The process is reversible, exchange capability being regenerated by washing the resin with an excess of the originally bound ions. The technology is utilized in many industrial applications such as chemical and biosynthesis, food processing and agriculture. In the pharmaceutical industry it is used to separate and purify proteins, nucle-otides and amino acids. Use in dosage form design may improve bioavailability of poorly soluble drugs, mask bitter taste and control drug release, either to enhance effectiveness or possibly inhibit narcotic abuse. Resins are also used as therapeutic agents for lowering cholesterol, potassium reduction and in chronic renal failure.
Johnson & Johnson, McNeil Consumer Healthcare, Fort Washington, PA, USA e-mail: [email protected]
C.G. Wilson and P.J. Crowley (eds.), Controlled Release in Oral Drug Delivery, 161
Advances in Delivery Science and Technology, DOI 10.1007/978-1-4614-1004-1_8, © Controlled Release Society 2011
Synthetic resins were introduced in 1935  and were first suggested in 1956 for sustaining drug release from dosage forms . The FDA approved the first IER product in 1958 viz Kayexalate®, for treating hyperkalemia. Resins have since been widely investigated for modifying oral drug delivery in particular but also for nasal , transdermal  and iontophoretically assisted transdermal  drug delivery, as evidenced by the plethora of patent applications covering the topic [6-8]. The high incidence of tobacco addiction in US stimulated the development of an IER nicotine chewing gum (Nicorette®) in 1984 which was a landmark IER therapy. Applications in oral controlled-release medications are discussed in this chapter.
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