Insolubilization test of sodium chondroitin sulphate with a view to its use as colonic carrier of drugs.

Several studies have been devoted to cross-linked sodium chondroitin sulphate (SCS), in the context of numerous strategies attempting to target the colon for the absorption or the therapeutic action of a drug. SCS, a glycosaminoglycan presenting a specific degradation in the colon, is in fact soluble in water and its use as drug carrier at such a distance from the digestive tube necessitates its hydrophobisation. One method described in the literature consists in manufacturing a three-dimensional network by cross-linking with bifunctional compounds. However, all the structural characterisations carried out on the products resulting from the catalysed treatments of SCS with diaminoalkanes demonstrate that there are no cross-linking bridges between the polymer chains. Moreover, treated SCS-based tablets containing theophylline as model drug lead in vitro to dissolution profiles which are identical to those obtained with the non-treated SCS. We were therefore unable to find the announced results using the method described.

Determination of phloroglucinol in human plasma by gas chromatography-mass spectrometry.

A specific and sensitive method has been developed for the determination of phloroglucinol in plasma; it involves an optimized procedure for blood sampling designed to minimize the in vitro oxidation of the molecule, and gas chromatography-mass spectrometry after silylation of the compound. The method allowed a reliable determination of phloroglucinol in plasma. The precision and accuracy of the assay, reported as coefficients of variation, were below 15%. Using a plasma sample of 0.25 ml, the limit of quantitation was 5 ng/ml with a precision of 17.4%, which is sensitive enough for pharmacokinetic studies. Stability studies under different conditions revealed that ascorbic acid limits the degradation of phloroglucinol in plasma during storage at freezer temperatures.