Application to drug delivery systems

Immobilization of Drugs and Application to Drug Delivery Systems. 

In the present chapter, several types of stimuli-responsive hydrogels are introduced, and their applications to drug delivery systems will be reviewed. 

Y. Kasuya, Z. R. Lu, R Kopeckova and J. KopeCek, Improved synthesis and evaluation of 17-substituted aminoalkylgeldanamycin derivatives applicable to drug delivery systems, Bioorg. Med. Chem. Lett., 11, 2089-2091 (2001). 

X. Ling, H.-P. Li,). Guo, Y.-W. Tang and l.P. Lai, Synthesis and characterization of molecularly imprinted polymeric microspheres for 1-methyldopa and its application to drug delivery system, Acfa Chim. Sinica., 68 (1) 95-101, 2010. 

Xylans from beech wood, corncobs, and the alkaline steeping liquor of the viscose process have been shown to be applicable as pharmaceutical auxiliaries [3]. Micro- and nanoparticles were prepared by a coacervation method from xylan isolated from corncobs [150]. The process is based on neutralization of an alkaline solution in the presence of surfactant, which was shown to influence both the particle size and morphology. They are aimed at applications in drug delivery systems. 

Since the purpose of this book is to describe applications of biodegradable polymers to drug delivery systems, particularly from the perspective of the materials employed, the approach taken in this chapter has been to focus on the natural biodegradable polymers which have been used most extensively as matrices for the delivery of drugs. Consideration was also given to the fact that collagen has not been the subject of any recent reviews. 

Because these types of polymeric matrix systems are the simplest to design and the easiest to obtain approval by the Food and Drug Administration, they have been the most extensively studied in the past two decades. Numerous polymers have been evaluated for these types of drug delivery systems and although it would be impractical to present each of these polymers and its specific application to drug delivery, this chapter will review in general the types of polymers used as matrices for drug delivery (1-4). 

Significant developments have occurred in recent years in the fields of biopolymers and biomaterials. New synthetic materials have been synthesized and tested for a variety of biomedical and related applications from linings for artifical hearts to artifical pancreas devices and from intraocular lenses to drug delivery systems. Of particular interest in the future is the development of intelligent polymers or materials with special functional groups that can be used either for specialty medical applications or as templates or scaffolds for tissue regeneration. 

The other significant factor concerns the viscosity of the transparent system which is low although, as one group claimed, it is unlikely to be non-Newtonian. Whether these considerations are relevant to the formation of spontaneous emulsions (later) remains to be seen but this whole area is one of considerable scientific interest, quite apart from its pharmaceutical application as drug delivery systems. 

Most of the studies on PLA degradation have concentrated on abiotic hydrolysis [35-37]. The effects of, e.g., residual monomer and other impurities, molecular weight and copolymerization on hydrolysis rate and properties have been studied [3,37-42]. Impurities, residual monomer [43,44], and peroxide modification [45] all increase the hydrolysis rate, while copolymerization can either increase (GA-copolymers) or decrease (CL, DXO-copolymers) the hydrolysis rate. Degradation of PLA and its copolymers in clinical applications ranging from absorbable sutures to drug delivery systems and artificial ligaments has also been widely studied [46-48]. 

It has to be clear that, once diluted and injected (or administered in ocular and other routes), the emulsion stability and fate are determined by three measurable parameters. The first is the partition coefficient of each emulsion component (including added drugs and agents) between the emulsion assembly and the medium. To some extent this partition coefficient is related to oil-water and/or octanol-water partition coefficients. For example, it was well demonstrated that per component of which logP is lower than 8, the stability upon intravenous (IV) injection is questionable [42,138], The other two parameters are kQff, a kinetic parameter which describes the desorption rate of an emulsion component from the assembly, and kc, the rate of clearance of the emulsion from the site of administration. This approach is useful to decide if and what application a drug delivery system will have a chance to perform well [89],... 

This article describes macrophage phagocytosis of polymer microspheres for the purpose of a deeper understanding of the polymer interaction with phagocytic cells. The provided information should contribute to the development of polymeric biomaterials, especially of polymer carriers applicable for drug delivery systems. 

Liposomes are widely investigated for their applicability as drug delivery systems. However, the unstable liposomal constitution is one of the greatest limitations, because the liposomes undergo fast elimination after application to the human body. In the presented study, novel archeal lipids were used to prepare liposomal formulations which were tested for their stability at elevated temperatures, at different pH-values and after heat sterilization. 

We have described here a novel approach to both the precise synthesis of the heterotelechelic PEGs and their application to drug delivery and gene delivery systems. Use of potassium 3,3-diethoxy-l-propananolate as an initiator of the polymerization of ethylene oxide not only produced various heterotelechelic PEGs but also end-functionalized PEG block copol5nners such as acetal-PEG-PLA, acetal-PEG-PAMA,... 

Yanagie, H., A. Ogata, H. Sugiyama, M. Eriguchi, S. Takamoto, and H. Takahashi. 2008. Application of drug delivery system to boron neutron capture therapy for cancer. Expert Opin. Drug Deliv. 5 427 43. 

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