Effect of small levels of impurities on the water vapor sorption behavior of ranitidine HCl.

PURPOSE

Deliquescence is the process by which a solid undergoes dissolution by sorbing moisture from its surroundings when a characteristic relative humidity, RH0, is reached. For mixtures of two or more deliquescent solids, RH0 will generally be lowered. The goal of this research was to investigate the effect of small amounts of impurities or degradants on RH0 for a model deliquescent pharmaceutical salt.

MATERIALS AND METHODS

The model salt chosen for this work was ranitidine HCl, which has two polymorphic forms. Moisture sorption profiles for each polymorph and samples of different purities were obtained using a gravimetric water vapor sorption balance.

RESULTS

Polymorphs of a similar purity yielded virtually identical moisture sorption profiles. In contrast, samples containing higher levels of impurities had both enhanced moisture sorption below RH0 and a lowered value of RH0.

CONCLUSIONS

It was concluded that small levels of degradants and/or impurities can drastically affect the moisture sorption profile of a deliquescent material, both through affecting the deliquescence relative humidity and by altering the overall interaction of the substance with moisture. Such changes in behavior may have significant effects on both active pharmaceutical ingredient and drug product stability during both processing and storage.