CHINOIN-137 consists of indometacin and beta-cyclodextrin in a 1 : 2 molar ratio. solid phase analytical techniques, as thermal analysis, mass spectrometry and X-ray powder diffraction do not support the existence of a well-defined crystalline complex. However this product dissolved in water more readily and results in a higher indometacin concentration than indometacin itself. The formation of an inclusion complex with a reasonable stability in aqueous solution was proved by diffusion tests and chiroptical properties. Following oral administration of CHINOIN-137 to rats, higher blood levels (by about 25%) of indometacin can be achieved than with the uncomplexed drug. A significant difference was observed in the absorption of 14C-labelled indometacin and its cyclodextrin complex by "in loco" techniques in the small intestines of anaesthetized rats: from indometacin 56%, from the complex 68% of the activity was resorbed within 10 min.