Photoisomerism of a vasodilator cinepazide maleate.

The photoinduced tautomerisation of cinepazide maleate ( 1), an effective vasodilator widely used in clinical therapy, had been investigated. It was found that (i) the higher the concentration of cinepazide maleate ( 1), the more stable it was; (ii) the effect of light on the photoisomerism of cinepazide maleate ( 1) was obvious in a suitable wavelength (e.g., 365 nm); (iii) solvents (e.g., acetone) with carbonyl chromophore absorbing UV could inhibit the generation of cis-isomer; (iv) anthranilic acid could be used as an effective ultraviolet absorbent and (v) the cinepazide maleate ( 1) could be properly stored under the airtight, light-free and room temperature conditions. [ABSTRACT FROM AUTHOR]