Chemically controlled drug delivery systems

Due to their sensitivity to electric stimulus, polyelectrolyte hydrogels have been investigated for their potential applications for electrically controlled drug delivery systems, electro-chemical actuators and sensors, as well as muscular actuators (Kaewpirom and Boonsang 2006). The set up for electrostimulation of... 

Details are given of pilocarpine trapped in a matrix diffusion-controlled drug delivery system using hydrophilic inserts of polyhydroxyethyl methacrylate. The physical and chemical properties of pilocarpine were investigated to determine the mechanism of drug-polymer interaction and the effect of drug release behaviour of controlled release polymeric devices. 22 refs. 

Microelectronic circuits for communications. Controlled permeability films for drug delivery systems. Protein-specific sensors for the monitoring of biochemical processes. Catalysts for the production of fuels and chemicals. Optical coatings for window glass. Electrodes for batteries and fuel cells. Corrosion-resistant coatings for the protection of metals and ceramics. Surface active agents, or surfactants, for use in tertiary oil recovery and the production of polymers, paper, textiles, agricultural chemicals, and cement. 

These discoveries generated a lot of effort over the successive 25 years in the preparation of especially designed drug delivery systems for the controlled release of radioactive progesterone [654], colchicine [656], naproxen [657,673, 674], mitomycin C [675-677], inulin [678], trimethoprin [657], succinylsul-fathiazole [657], ethacrynic acid [653], and steroids [633], regardless of whether these drugs are physically trapped in polyphosphazene matrices, or chemically bonded to the polymer skeleton. 

V. J. Stella, T. J. Mikkelson, and J. D. Pipkin, Pro-drugs The control of drug delivery via bioreversible chemical modification, in Drug Delivery Systems Characteristics and Biomedical Applications (R. L. Ju-liano, ed.), Oxford University Press, New York, 1980,... 

Poly-j3-malate is readily degraded completely to L-malic acid under both acid and base conditions [108], and it can also be hydrolyzed by enzymes within the cell [105,106]. Recently, several bacteria were isolated which were able to utilize poly-/i-malate as sole carbon source for growth [109]. Because the polymer is biodegradable and bioadsorbable, it is of considerable interest for pharmaceutical applications, especially in controlled-release drug delivery systems [97,98]. Chemical routes to poly-/ -malate are expected to provide materials with various properties [110]. 

Michael J. Groves, a pharmacist with a doctorate in chemical engineering, has spent much of his career working in industry and academe. Now retired, his scientific interests include dispersed drug delivery systems and quality control issues for parenteral drug products. Editor or joint editor of a number of books, he has published 400 research papers, patents, reviews, and book reviews. He is a Fellow of the Royal Pharmaceutical Society of Great Britain, the Institute of Biology, and the American Association of Pharmaceutical Scientists. 

Chitosan has been the focus of reasearch as a pharmaceutical excipient due to its specific chemically and biologically favorable features [6-8]. As chitosan is soluble in acidic aqueous solutions, it can be processed under acidic conditions. By contrast, as the product made by chitosan is insoluble at neutral or basic pH, it behaves as a delivery system under such conditions. These chemical properties allow chitosan to control drug delivery. Further,... 

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