Polarographic behaviour of 2-(5-nitro-2-furyl)-5-(2-aminoethoxy)- pyrimidine derivatives.

Polarographic reduction of the title compounds in mixtures of Britton-Robinson buffers and methanol (1:1) or DMF (3:1) for compound 10 at the pH range of 2.8--11.3 is described. In strongly acid medium the compounds were reduced in two diffusion governed waves corresponding to the consecutive reduction of NO2-group (6-electron wave) and pyrimidine ring (2-electron wave) to amine and dihydropyrimidine, respectively; with increasing pH the second wave became, however, much worse shaped. In alkaline medium a third wave appeared, the limiting current of which corresponded to a 2-electron process; the wave corresponds probably to the further reduction of pyrimidine ring to tetrahydroderivative. Mechanism of the reduction of the title compounds has been suggested and discussed.

Polymorphism of indomethacin. Part II. Identification and rapid determination of polymorphic forms of indomethacin by IR spectrometry.

A procedure is described, which make it possible to determine the content of individual polymorphic forms of indomethacin in their mixture by IR spectrometry. IR spectra recorded in the range of 1600--1800 cm-1 have been used in the determinations. The method is especially useful for analytical control of the technological process of preparing the most pharmacologically active-gemma-form of indomethacin.

Polymorphism of indomethacin. Part I. Preparation of polymorphic forms of indomethacin.

Technologically useful methods of preparing defined polymorphic forms of indomethacin (especially gemma-form) have been described. The influence of various crystallization parameters on the formation of individual form of indomethacin have been discussed.