Controlled release systems transdermal

Transdermal controlled-release systems can be used to deliver drugs with short biological half-lives and can maintain plasma levels of very potent drugs within a narrow therapeutic range for prolonged periods. Should problems occur with the system or a change in the status of the patient require modification of therapy, the system is readily accessible and easily removed. 

Cleary GW. Transdermal controlled release systems. In Langer RS, Wise DL, eds. Medical Applications of Controlled Release. Vol 1. Boca Raton, FL CRC Press, 1983 203-251. 

Figure 2.6 Hypothetical blood level pattern from a conventional multiple dosing schedule, and the idealized pattern from a transdermal controlled release system.

Figure 9.2 Reservoir delivery systems based on rate-limiting polymer membranes. Rate-limiting polymer membranes can be used to produce several different types of drug delivery devices including (a) transdermal delivery systems, (b) planar con-trolled-release systems, and (c) cylindrical controlled-release systems.

Cellulose from a different source, bacterial cellulose, also known as microbial cellulose, has been the focus of recent research studies [30]. Microbial cellulose possesses some superior characteristics compared to plant cellulose, including high purity, waterholding capacity (aroxmd 1000%), crystallinity (around 90%), nanofibrilar network, impressive mechanical strength, and in-situ moldability [26,27]. The studies were related to use of microbial cellulose as a nanomaterial in controlled-release systems [30] and transdermal formulations [31]. 

C. Bodhibukkana, S.T. Kaewnopparat, N. Tangthong, P. Bouking, G.P.R. Martin, Suedee bacterially-derived composite membranes of cellulose cuid molecularly imprinted polymer for use as a transdermal enantioselective controlled-release system of racemic propranolol, /. Controlled Release, 113,43-56,2006. 

Current controlled transdermal-release systems can be classified into four types, as follows, with a representative product and manufacturer ... 

As pharmaceutical scientists gain experience and tackle the primary challenges of developing stable parenteral formulations of proteins, the horizons continue to expand and novel delivery systems and alternative routes of administration are being sought. The interest in protein drug delivery is reflected by the wealth of literature that covers this topic [150-154]. Typically, protein therapeutics are prepared as sterile products for parenteral administration, but in the past several years, there has been increased interest in pulmonary, oral, transdermal, and controlled-release injectable formulations and many advances have been made. Some of the more promising recent developments are summarized in this section. 

Cormier M, et al. Transdermal delivery of desmopressin using a coated microneedle array patch system. J Control Release 2004 97 503-511. 

Knepp, V.M., F.C. Szoka, and R.H. Guy. 1990. Controlled drug release from a novel liposome delivery system. II. Transdermal delivery characteristics. J Control Release 12 25. 

Scott, E.R., et al. 2000. Electrotransport systems for transdermal delivery A practical implementation of iontophoresis. In Handbook of pharmaceutical controlled release technology, ed. D.L. Wise. New York Marcel Dekker, chap. 31. 

The purpose of this overview chapter is to provide perspectives in the current status and future prospects of controlled release drug delivery. This is accomplished by examining various delivery systems from a mechanistic point of view, exploring applications of these systems, and discussing relevant biopharmaceutical parameters. A major section of this book is devoted to fundamental issues and applications of transdermal and transmucosal delivery systems (Chapter 6,8,17-23). Other developing systems of future potential... 

Sugibayashi, K., and Morimoto, Y. (1994), Polymers for transdermal drug delivery systems, I. Controlled Release, 29,177-185. 

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