[Lyophilisation of protein-based drugs]. / Lyofilizácia lieciv na báze proteínov.

Lyophilisation is a well-established method for drying of various substances with a wide range of applications in the pharmaceutical area. During the last decade its relevance increases with a number of therapeutically used proteins. A sensitive protein drug may undergo several changes, like unfolding and loss of activity due to various stresses during the lyophilisation process. Understanding of these processes (freezing, primary drying, secondary drying) is fundamental for manufacturing of a drug product with desired properties, namely its safety and efficacy. In order to reduce costs and increase the quality, new technologies are being rapidly developed and established in industrial lyophilisation (e.g. process analytical technologies, control nucleation techniques).

In vitro liberation of indomethacin from chitosan gels containing microemulsion in different dissolution mediums.

The objective of this research is to outline the liberation of indomethacin from different chitosan gels containing O/W microemulsion. The influence of surfactant, sodium lauryl sulfate, in two concentrations (0.5% and 0.75%, w/w) was determined in dissolution medium on the release of indomethacin, which was used as poor water-soluble model drug. Chitosan gels were prepared in four different concentrations of chitosan-1%, 1.5%, 2%, and 3% (w/w). Microemulsion enhanced the liberation of the indomethacin from chitosan gels into all dissolution mediums. Adding the surfactant into phosphate-buffered saline decreased the amount of liberated indomethacin from microemulsion, gel mixture, but increased the drug liberation from pure chitosan gels. It was detected that with the increased concentration of chitosan in the samples, the amount of indomethacin liberated (p < 0.05) also increased. A conclusion was drawn that the liberation of indomethacin from chitosan gels was influenced by increased pH of the samples. The high viscosity induced a higher release of indomethacin from 3% (w/w) chitosan hydrogel at pH 5.8 as compared with 3% (w/w) chitosan hydrogel at pH 3.8. The highest percentage of released indomethacin was determined when a mixture of microemulsion gel with higher chitosan content was used.