THE EFFECTS OF AGING ON THE THERMAL-BEHAVIOR AND MECHANICAL-PROPERTIES OF PHARMACEUTICAL GLYCERIDES

The thermal behaviour of stored Gelucires 43/01, 50/02, 54/02, 50/13 a nd 55/18 has been studied, particularly with a view to examining the r elationship between preparation conditions and physical stability. The endotherms of Gelucire 43/01 samples were found to approach an equili brium shape on storage, with samples which had been fast cooled from t he melt adopting this shape over the shortest period of time. Temperin g of these materials at elevated temperatures resulted in alterations in the distribution of endotherms and represents a possible method of accelerating the transition to the equilibrium form. Ageing of Gelucir es which contain mixes of glycerides and polyethylene glycol (PEG) est ers resulted in changes in the endotherm shape but no evidence for an equilibrium profile was obtained. Studies on Gelucire 55/18, which con tains only PEG esters, showed that the main endothermic peak exhibited little evidence for ageing effects, although a lower temperature shou lder was observed on storage. Tensile strength (a) measurements indica ted that the strength of the Gelucires also changed on storage. It was noted that materials containing either glycerides or PEG esters tende d to show an increase in a on storage, while Gelucires containing a mi xture of the two components showed a decrease in strength.