Synthesis, characterisation and drug release pattern of certain lactic acid based random copolyesters

Biodegradable synthetic polyesters have recently found widespread application in biomedical and engineering fields, such as tissue engineering, therapeutic delivery and bioimaging. Currently, many applications involving lactic acid based polyesters are being explored with polymers derived from monomers that are endogenous to the human metabolism. In terms of mechanical stability, crystallinity, hydrophobicity and biocompatibility, polyesters synthesised from these monomers can display a wide range of applications. In this investigation, a series of novel biodegradable copolyesters synthesised from lactic acid, terephthalic acid and ethylene glycol/1,4 butane diol through a two step process of melt polycondensation using titanium tetra isopropoxide as catalyst. The synthesised random copolyesters were characterised by means of solubility, viscosity measurements, IR, ¹H NMR, ¹³C NMR spectral analysis and hydrolytic degradation tests. The copolyesters remained unchanged in simulated gastric fluid (pH -1.2) and gradually degraded in simulated intestinal fluid (pH – 7.4). They were later tried as enteric coating materials on diclofenac sodium core tablets and their drug release patterns correspond to BP standard drug release profile of enteric coating material