The market of transdermal drug delivery systems is significantly and steadily growing in USA and European markets. Extended release formulations such as transdermal and implant drug delivery systems may release drugs in patients for periods ranging from days to years. For such large periods of time, the current drug testing, and accompanying regulatory issues may be complex and potentially faulty, as the real time drug release is too long to be followed adequately. Accelerated drug release tests shown to correlate with real time drug release are needed to minimize drug manufacturing time, assure drug availability in the market, ensure adequate in vivo drug release in patients over long periods of time, and minimize overall drug costs. A preliminary review of the literature indicates that there is potentially unclear regulatory guidance, nonsignificant research and poor theoretical understanding of the field of accelerated drug dissolutions.
In this study we propose to increase the understanding and develop the kinetics theory of accelerated drug release in transdermal drug delivery systems using clonidine patches with 7-day drug dissolutions tests as a model. Current drug dissolution tests of many patches last over 96 hours with only a few samples taken for analysis. The accelerated drug releases observed for the clonidine transdermal delivery systems will be compared with real time drug releases of the same formulations using chemical kinetic approaches. The acceleration of the drug release will be induced mostly by changes in the dissolution media pH, temperature, and dielectric constant.
This project is the start of a series of studies on accelerated dissolution rates of extended release drug delivery systems including tablets, transdermal patches, and implants of various drugs currently available or close to approval for sale in the market.