Encapsulation of indomethacin in PVP: Solid-state NMR studies

C-13 solid-state NMR and H-1 relaxation time measurements have been used to determine the structure of the crystalline and amorphous forms of the pharmaceutical drug indomethacin. Cross-polarization dynamics parameters were calculated for individual NMR resonances providing an insight into the mobility of functional groups in two forms of indomethacin. The changes of mobility in indomethacin/ polyvinylpyrrolidone (PVP) formulation have been investigated via(1)H-C-13 solid-state NMR methods. Differences between the amorphous material and its crystalline counterpart have been observed. The gamma-amorphous indomethacin rapidly crystallizes with time. it has been shown that encapsulation in the PVP stabilizes the amorphous form of the drug by preventing crystallization due to reduced mobility of the guest in the formulation.