Studies on the compatibility of diethylpropion hydrochloride with carboxymethylcellulose and other dietary fibres.

The combination of diethylpropion hydrochloride with carboxymethylcellulose induces decomposition of the drug. The principal decomposition products obtained were 1-phenyl-1,2-propanedione, benzoic acid and diethylamine as hydrochloride and benzoate salts. These phenomena have been explained with reference to basic decomposition scheme of the diethylpropion. Additionally, the behaviour of diethylpropion in mixtures with other dietary fibres such as methylcellulose, wheat bran and wheat germ was examined. Diethylpropion in combination with methylcellulose is rather stable while in mixtures with wheat bran and wheat germ suffers degradation. An increase in the weight of the excipient, probably due to chemical binding of the drug and other degradation products by the excipient, was observed in all these cases. The decomposition reactions were studied by applying a sequence of selective solvent extractions and using high-performance liquid chromatography (HPLC).

Relationship between composition and structure in chitosan-based hybrid films.

Chitosan/poly(aminopropylsiloxane) hybrid films were obtained by blending 3-(aminopropyl)siloxane oligomers (pAPS) with chitosan (CHI). The pAPS oligomers were prepared by the sol-gel method starting from 3-(aminopropyl)triethoxysilane. These hybrids were characterized by chemical, spectroscopic and morphological methods. Scanning electron micrographs of hybrid films of different composition revealed an organized microscopic pattern suggesting the existence of systematic interactions among their components. Comparison of the thermal stabilities and X-ray diffraction patterns as well as FT-IR spectra of the films with those of the pure components revealed that nanocomposites were formed. Similar studies of films including lithium perchlorate, as a third component, showed that addition of certain amount of lithium ions affected the structure of the CHI/pAPS films. When addition of the lithium salt exceeded the homogeneous incorporation limit, a little excess generated anisotropically oriented patterns in the hybrid films.