Gamma scintigraphy in the analysis of ketoprofen behaviour from matrix tablets

The aim of this work was to study in vitro and in vivo the behaviour of matrix tablets (quick and extended release) containing ketoprofen (KTP) as a model drug and cellulose ether polymers, using gamma scintigraphy. The matrix tablets were prepared by the direct compression method and labelled by incorporating a drop of technetium ((99m)Tc). It was spectrophotometricaly confirmed that the radioisotope inclusion did not modify the kinetics of KTP release. In vitro studies were carried out for the tablets using the paddle method of the USP 35/NF30. The images were processed by defining regions of interest over the tablet (99m)Tc and the percentage of remaining activity/time curves were generated for both formulations. In vitro gamma scintigraphy studies showed significant differences (p<0.05) between both formulations. Identical results were obtained from the in vivo studies. In vivo tests were performed on five healthy volunteers. The scintigraphy images were acquired during 2.5 and 7.5h for quick and extended release formulations, respectively. The position of the extended release formulation tablet along the gastrointestinal tract (GIT) was assessed. The described results demonstrate the in vitro/in vivo correlation for the drug release profile and exhibit the importance of gamma scintigraphy for the drug location through the GIT.