Characterization of drug loading in crospovidone by X-ray photoelectron spectroscopy.

The mechanism of drug loading in cross-linked polymers was studied by X-ray photoelectron spectroscopy (XPS). This gave the atomic composition of the surface layers of the loaded polymeric particles so that the exact location of the drug molecules could be identified. Three different lots of popcorn crospovidone and a chemically cross-linked povidone were loaded by solvent swelling, with griseofulvin chosen as the drug model. The resulting drug-polymer systems were characterized by XPS, differential scanning calorimetry, X-ray diffractometry, and electron scanning microscopy. The XPS technique was found to give interesting information on the griseofulvin distribution in the polymeric particles.