Topical delivery systems

Topical Delivery Systems Topical delivery systems are self-contained, discrete dosage forms that are designed to deliver drug via intact skin or body surface, namely transdermal, ocular, and intrauterine. 

As with many other delivery systems, topical application of liposomes attracts a lot of attention. Over the years, topical pigs delivery of liposomes was tried for different purposes and in different models. In general, liposomes were found... 

Polyphosphazenes can be considered as biomaterials in several different ways, depending on the type of utilization one can predict for these substrates. In this regard, we will consider three different topics concerning water-soluble POPs and their hydrogels, bioerodible POPs for drug delivery systems and for tissue engineering, and the surface implications of POP films. 

We are learning more and more that the conditions of use of topical delivery systems have a profound... 

Topical Delivery—Attributes of Topical Delivery Systems... 

We tend to think of them being much the same, but the functioning of semisolid dermatological products stands in stark contrast with that of transdermal delivery systems. To begin with, most topical applications... 

The eye is unique in its therapeutic challenges. An efficient mechanism, that of tears and tear drainage, which quickly eliminates drug solution, makes topical delivery to the eye somewhat different from most other areas of the body [137]. Usually less than 10% of a topically applied dose is absorbed into the eye, leaving the rest of the dose to potentially absorb into the bloodstream [138], resulting in unwanted side effects. The goal of most controlled-delivery systems is to... 

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. 

Another circumstance in which there may be generally compelling reasons to require quantification of active metabolites is when a controlled-release drug-delivery system is used for a drug that has an active metabolite. Some of the papers that consider the topics of bioequivalency testing for drugs with long half-lives or active metabolites are listed in the references section of this chapter [12-17]. 

Nagai T (1985) Adhesive topical drug delivery system. J. Control. Rel. 2 121-134. 

Topical spermicides such as nonoxynol-9 (N9) and benzalkonium chloride act on sperm membranes through a detergent effect, namely, hydrophobe-hydrophobe interaction between the active and substrate (spermatozoa). The idea was to optimize the cationic/hydrophobic polymer in the drug delivery system so epithelial cells were protected without sacrificing the drug s spermicidal activity. One of the questions that needed to be answered in designing an optimum cationic/hydrophobe modified polymer was the effect of the hydrophobe on the drug activity (N9 initially, and other actives subsequently). 

Machida, Y., and Nagai, T. Bioadhesive Preparations as Topical Dosage Forms. In Bioadhesive Drug Delivery Systems (E. Mathiowitz, D.E. Chickering, III, and C.-M. Lehr, eds.), Marcel Dekker, Inc., New York, 1999, pp. 641-657. 

Mezei, M. and Gulasekharam, V, Liposomes a selective drug delivery system for the topical route of administration gel dosage form. J. Pharm. Pharmacol., 34,473-74, 1982. 

Mezei, M. and Gulasekharam, V., Liposomes — a selective drug delivery system for the topical route of administration lotion dosage form. Life ScL, 26, 1473-77, 1980. Fresta, M. and Pughsi, G., Survival rate improvement in a rat ischemia model by long circulating liposomes containing cytidine-51-diphosphate choline. Life ScL, 61, 1227-35, 1997. 

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