Gamma irradiation effects on poly(DL-lactictide-co-glycolide) microspheres.

Gamma radiation treatment plays an increasingly important role in the sterilization/sanitization of pharmaceutical products. However, irradiation may affect the stability of the product and thus its safety of use. We investigated the influence of ionizing radiation on modified release microparticulate drug delivery systems made of two types of polylactide-co-glycolide copolymers (PLG): RG 503 and RG 503H; these polymers have identical molecular weights but different chemical structures.

Investigation of a new amoxicillin sodium impurity unstable in solution.

A new amoxicillin sodium impurity was detected by reversed-phase HPLC in commercial injectable preparations only when examined very soon after the drug was dissolved in the solvent vial (within about 10 min). The stability of this impurity was investigated by the degradation kinetic of its aqueous solutions. Ionspray mass spectrometry with flow-injection analysis and HPLC-MS methods were used to establish its nature.

Liquid oxygen contaminants--increase in concentration during use of domiciliary liquid oxygen medical systems.

The quality of liquid oxygen in domiciliary medical systems used for oxygen therapy was investigated during the emptying cycle under simulated breathing conditions. The increase in the levels of contaminants during the use of these systems was evaluated by gas chromatography and two sampling methods. The quality of liquid oxygen from storage tanks located in hospitals and in the production or in distribution plants was also investigated.

Activity coefficients and partition coefficients as parameters for the evaluation of biological activity. A linear relationship between log "gamma" and log P.

The activity coefficient (gamma) and the partition coefficient n-octanol/water (P) of various groups of substances of pharmaceutical and biological interest (anaesthetic gases, primary n-alcohols and barbiturates) were compared in order to obtain a linear relationship. Considering n-octanol as an ideal solvent, the curve of the behaviour of any real substance with the system n-octanol/water has an inclination of 45 degrees (delta log "gamma"/delta log P = 1). By means of the n-octanol/water partition coefficient the activity coefficient can be calculated in order to evaluate the biological activity of the groups of substance examined.