Effect of aging on the release of salbutamol sulfate from lipid matrices

The aim of the present work was to evaluate the influence of aging that might condition the release of salbutamol sulfate from oral formulations (lipid matrices) using Gelucire® as lipid excipients. Gelucires are essentially characterized by their melting point and their hydrophilic-lipophilic balance. The release profiles of salbutamol sulfate from the capsules elaborated were dependent on the type of Gelucires, fast release, in the case of Gelucire® 35/10, a slower release for Gelucire® 48/09 and a slow release for Gelucire® 46/07. Differential scanning calorimetry was used to study the physical state of drugs in the matrices. Gelucires may exhibit aging effects, whereby a range of physical properties may change upon storage. In the case of Gelucire® 35/10, which presents a fast release of salbutamol sulfate, storage produces a decrease in the values of dissolution constant for all capsule sizes. Gelucire® 48/09 showed a slower release rate than Gelucire® 35/10, and after 1 year of storage, a decrease in the salbutamol dissolution rate for capsule number 3 and 4 was observed. Gelucire® 46/07 presented the slowest dissolution rate, but there were not statistically significant differences. These results show that the faster the dissolution rate, and the larger the capsule size, the higher is the influence of storage. (C) 2000 Elsevier Science B.V.