Homogeneity study of ointment dosage forms by infrared imaging spectroscopy

Ointment dosage forms are semi-solid preparations intended for local or transdermal delivery of active substances usually for application to the skin and it is important that they present a homogeneous appearance. In this work, a study of the homogeneity of a tacrolimus ointment dosage form was performed using infrared imaging spectroscopy coupled with principal component analysis (PCA) and multivariate curve resolution with alternating least squares (MCR-ALS) to interpret the imaging data. Optical visible microscopy images indicated possible phase separation in the ointment and, based on the results presented by distribution concentration maps from infrared imaging, it was possible to conclude that, in fact, there was phase separation incorporated in the ointment. Thus, infrared imaging spectroscopy associated to PCA and MCR-ALS is demonstrated to be a powerful tool for the development process of ointment dosage forms.