Chemical Imaging of Oral Solid Dosage Forms and Changes upon Dissolution Using Coherent Anti-Stokes Raman Scattering Microscopy(full pdf)
Maike Windbergs, Martin Jurna, Herman L. Offerhaus, Jennifer L. Herek, Peter Kleinebudde, and Clare J. Strachan
vol 81, issue 6 p2085-2091 march 11 2009
Dissolution testing is a crucial part of pharmaceutical dosage form investigations and is generally performed by analyzing the concentration of the released drug in a defined volume of flowing dissolution medium. As solidstate properties of the components affect dissolution
behavior to a large and sometimes even unpredictable extent there is a strong need for monitoring and especially visualizing solid-state properties during dissolution testing.
In this study coherent anti-Stokes Raman scattering (CARS) microscopy was used to visualize the solid-state properties of lipid-based oral dosage forms containing the model drug theophylline anhydrate during dissolution in real time. The drug release from the dosage form matrix was monitored with a spatial resolution of about 1.5 μm.
In addition, as theophylline anhydrate tends to form the less soluble monohydrate during dissolution, CARS microscopy allowed the solid-state transformation of the drug
to be spatially visualized. The results obtained by CARS microscopy revealed that the method used to combine lipid and active ingredient into a sustained release dosage
form can influence the physicochemical behavior of the drug during dissolution. In this case, formation of theophylline monohydrate on the surface was visualized during
dissolution with tablets compressed from powdered mixtures but not with solid lipid extrudates.