Polyanhydrides fatty acid-based

Several combinations of monomers used to prepare polyanhydrides are classified as aliphatic, aromatic, aliphatic-aromatic, amine-based, and fatty acid-based polyanhydrides. The structures of these monomers determine... 

Polyanhydrides Polyanhydrides have a hydrophobic backbone with a hydrolytically labile anhydride linkage. These polymers widely vary in chemical composition and include aliphatic, aromatic, and fatty acid-based polyanhydrides. The rate of degradation depends on the chemical composition of the polymer. In general, aliphatic polyanhydrides degrade more rapidly than the aromatic polymer. Hence, copolymer blends with varying ratios of aliphatic-to-aromatic polyanhydrides can be synthesized to suit specific applications. 

Fatty acid-based polyanhydrides derived from dimers or trimers of unsatirrated fatty acid, which have two carboxylic groups available for the reaction. Natural fatty acids possess only one reactive group and can be employed as chain terminators. Chemical and physical properties can be modulated by choosing adequate monomers and their relative amount. 

Some important groups of polyanhydrides already in medical use are based on para-(carboxyohenoxy)propane, para-(carboxyphenoxy)hexane, para-(carboxyphenoxy) methane and their copolymers with sebacic acid. Also reported has been the use of fatty-acid-based polyanhydrides synthesized from hydrophobic dimers of erucic acid and sebacic acid in drug release applications [456]. They also follow surface erosion degradation [457]. As the polymer degrades, the fatty acid monomers deposit on the surface of the polymer matrices and act as an obstacle to the diffusion of low molecular weight compounds (e.g., active small molecules), contributing to slow release [458]. 

The second approach was applied in the synthesis of fatty acid terminated polyanhydrides. Polyanhydrides based on sebacic acid, and terminated with oleic, stearic, linoleic or lithocholic acid, or combinations of several fatty acids were synthesized 21). The general structure of fatty acid terminated polyanhydrides is shown in Figure 1. 

Fatty acid based biodegradable polymers have many biomedical applications. This short review focuses on controlled drug delivery using two classes of the polymers polyanhydrides and polyesters based on fatty acids as drug carriers. Different polymer types and compositions are summarized showing the potential of these polymers as drug carriers. 

M Maniar, AJ Domb, A Haffer, J Shah. Controlled-release of a local anesthetic from fatty-acid dimer based polyanhydride. J Controlled Release 30 233-239, 1994. 

Polyanhydrides based on unsaturated and fatty acid-derived monomers are shown in Table III. Poly(fumaric acid) (PFA) was fist synthesized by Domb et al. (1991) by both melt polycondensation and solution polymerization. The copolymer of fumaric acid and sebacic acid (P(FA-SA)) has been synthesized and characterized (Domb et al., 1991 Mathiowitz et al., 1990b). The mucoadhesive properties of this polymer... 

Recently, a new polyanhydride, poly(fatty acid-sebacic acid), has been synthesized. This polyanhydride uses hydrophobic dimers of erucic acid. Some of its physical properties relevant to the fabrication of drug delivery devices are also improved over those of the other anhydrides based on CPP lower melting temperature, higher solubility in solvents, and higher mechanical strength. The erosion of the polymers is dependent on... 

Fatty acids have been used previously in the development of polymers for biomedical applications as they are considered to be inert, inexpensive and biocompatible. The main fatty acids which are used as a base for synthesis of biomedical polymers (polyanhydrides) are stearic acid (/), erucic acid (C22 unsaturated fatty acid) dimer (2), bile acid dimer (i), ricinoleic acid 4) and other fatty acids (5), middle long carbon chain (C12 - 15) dibasic acids, such as dodecanedioic, brassylic acid, tetradecandioic acid and pentadecandioic acid (/). 

Recently, a new family of polyanhydrides has been explored (Domb et al, 1987 Tabata and Langer, 1993). These copolymers are based on fatty acid dimers derived from oleic and sebacic acids (6) and are termed... 

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