Development of drug delivery systems

Historically, in the search to improve both quality and length of life, humans have made successive developments in hygiene and nutrition that helped to increase life span. In the last few centuries the growth in medical knowledge has greatly contributed to the improvement of human health, and as a result fife expectancy has increased in many parts of the world. At the same time, many attempts have been made to improve the comfort of fife, and textile-based systems are particularly useful here since these products are iu direct contact with the human body. The delivery of drugs by textile materials is therefore au important means to improve the quality of life for people with various medical couditions. 

Textile materials can be made with permeable and breathing structures, and treated to have an absorptive capacity. In addition, many novel base materials have been developed to carry drugs in a fibrous structure. For example, chitosan is a partially 

Controllability is an important aspect of a delivery system. Preferably, a system should be controlled in such a way that the release of drugs is possible within a certain range, so that with any given system different release patterns should be feasible to respond to an individual patient s specific need. Material costs are also important. Commercially, there is no use in developing a drug delivery system in which the benefits are canceled out by the costs. To reduce costs, conventional production techniques are often beneficial in comparison to specially developed new techniques. 

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More recently, we have seen the development of drug delivery systems as a specialized sector in the pharmaceutical industry. This whole concept is based on the interaction of excipients with the API and manufacturing process, and sometimes with other excipients, to produce a formulation of a medicinal product that meets a particular performance specification. 

For the development of drug delivery systems it is of fundamental importance to achieve the co-precipitation of drugs and biodegradable polymers. The supersaturation working conditions of S AS allow, in many cases, fast and simultaneous precipitation of both polymer and drugs, so that the drugs can be trapped into the polymer matrix. A list of the coprecipitation experimental results is reported in Table 9.9-5. 

Sunkara, G. andChilukuri, D., IVIVC an important tool in the development of drug delivery systems, Drug. Del. Tech., 3, 52, 2003. 

One of the earliest approaches to creating polymer-peptide hybrid materials was based on the introduction of peptide moieties in the polymer side chain [11]. These architectures have been of particular interest for the development of drug delivery systems with a high loading capacity as well as for systems in which case the bioactivity is related to having multiple copies of a peptide in close proximity of each other. 

Nishida K. [Development of drug delivery system based on a new administration route for targeting to the specific region in the liver]. Yakugaku Zasshi 2003 Aug 123(8) 681-689. Japanese. 

In the last 15 to 20 years, there has been a huge resource in both academia and industry devoted to the development of drug delivery systems that target drugs more effectively to their therapeutic site. Much of this work has been successful and is reported within this text. In spite of this, oral solid dosage forms such as tablets and hard gelatin capsules, which have been in existence since the nineteenth century, remain the most frequently used dosage forms. This is not simply a reflection of the continued use of established products on the market, tablets and capsules still account for about half of all new medicines licensed (Table 11.1). 

Initially polymers were used as solubilizers, stabilizers, and mechanical supports for sustained release of drugs. However, over a period of time, the functionalities of polymers have changed. The polymers have been synthesized and designed to suit specific needs or rather solve specific problems associated with development of drug delivery systems. 

An outstanding approaeh for the development of drug delivery systems has been recently presented by Zhang and Ma [99], In this work, the use of a P-cyclodextrin (P-CD) containing DHBC has been proposed for the inclusion of many hydrophobic substances. In their work, the synthesis of a bloek eopolymer with a PEG block and a polyaspartamide block carrying some P-CD units has been described. The P-CD imits are used as host sites for a plethora of hydrophobic small molecules, like pyrene and comnarine, as well as for hydrophobic polymers. However, the formation of inclusion complexes leads to the creation of located hydrophobic areas within the copolymer domain, which, in turn, has as a result the formation... 

In biomedical science, fatty acids have been investigated as carriers or for the development of drug delivery systems as they are considered to be endogenous, cost-effective and biocompatible. Stearic acid is a long-chain of 18 carbon atoms saturated fatty acid atoms which is the main component of fat. Initially, it was used for candle production. 

This polymer has been used in several medical applications already approved by the U.S. Food and Drug Administration. Recently, PCL is being applied not only in the development of drug delivery systems [42] and resorbable sutures [43], but also as a material for tissue regeneration [44]. 

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