The influence of water content of triglyceride oils on the solubility of steroids.

PURPOSE: To determine if hydration of long- and medium-chain triglyceride oils (long = soybean and olive, medium = Miglyol 812) has a significant effect on the ability to solubize the model hydrophobic compounds progesterone, estradiol, and testosterone.

METHODS

Soybean, olive, and Miglyol 812 oils were treated in one of two ways: hydrated or desiccated (hydrated, then dried). Solubility of (3)H-labeled progesterone, estradiol, and testosterone in the triglycerides was measured by liquid scintillation counting.

RESULTS

Both hydration state and chain length of the triglycerides were shown to have a significant influence on the solubility of steroids. Solubility of estradiol hemihydrate and testosterone monohydrate in hydrated triglycerides is decreased by about 30%-40% compared with desiccated oils. The solubility of anhydrous testosterone was decreased by hydration of the oils due to conversion to the monohydrate crystalline form. In contrast, the solubility of progesterone was insensitive to the state of hydration of all oils.

CONCLUSIONS

Hydration of triglyceride oils caused a significant decrease in the solubility of steroids, which may form hydrates or hemihydrates. Results suggest the need for knowledge of the hydration state of triglyceride oils to be used as pharmaceutical excipients.