Drug release from a new family of biodegradable polyanhydrides

Studies investigating the mechanism of drug release from poly (fatty acid dimer:sebacic acid) {p (FAD : SA)} polyanhydride are described. Acid orange (A.O.), a hydrophilic dye and Rhodamine B Base, a hydrophobic dye, were used as models. Light microscopy indicates there is a drug depleted zone which grows wider with time. The effect of drug incorporation method on release was also investigated. An emulsion method greatly reduced A.O.'s 'burst effect'. The effect of copolymer properties (e.g., hydrophobicity, crystallinity), drug properties (e.g., solubility) and drug loading on release was also investigated. A.O. release was affected by copolymer composition, and exhibited faster release than the more hydrophobic dye, Rhodamine B Base. Correlations between drug release and underlying polymer erosion are also described.