Polymers for drug delivery

Article By:

Siegwart, Daniel J. Harold C. Simmons Comprehensive Care Center, University of Texas Southwestern Medical Center, Dallas, Texas.

Last reviewed:2014

DOI:https://doi.org/10.1036/1097-8542.YB150544

The field of drug delivery has been through a few eras of advancement. Early efforts were simply directed at using polymers to enable the slow release of drugs. This was done to mitigate side effects, enable prolonged drug action over time, and increase the bioavailability of drugs in the body. The next phase focused on achieving zero-order (steady) drug-release profiles. It was thought that having a constant concentration of a drug would provide an optimal therapeutic effect. Most likely, a system that enables the concentration of a drug to remain above the minimum effective dose and below the maximum toxic dose (within the so-called therapeutic window) will improve the efficacy and duration of therapy. Scientists are currently in a third era of “smart” drug delivery, where researchers are seeking to design drug delivery systems that can release drugs on demand, in response to specific stimuli. This can include pH, temperature, specific enzymes, and other forms of triggers. Scientists would also like to have better control of the interactions of polymer nanoparticles with biological fluids and proteins in the body. Therefore, polymers for drug delivery are now being called upon to perform many functions. These include increasing the time that drugs are available (in blood circulation or in the tissue), mediating the biodistribution (the location of the drug in the body), improving the solubility of drugs (for example, hydrophobic, water-insoluble small-molecule drugs), improving the stability of drugs (for example, nucleic acid or protein drugs), providing active or passive transport of the drug to targeted tissues, enabling controlled release of the drug in response to stimuli, and controlling the specific interaction of the drug with biomolecules in the body. Recently, a number of advancements have been made that will have a positive effect on the future of drug delivery using polymers. A few of them are highlighted in this article.

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