A COMPREHENSIVE DETERMINATION OF THIORIDAZINE AND ITS METABOLITES IN URINE

A comprehensive method for the determination of urinary thioridazine and its metabolites is reported. It is based on adsorption of total urinary drug to a cation exchange resin, from which the drug content is subsequently eluted with 50% sulfuric acid. Subtle differences in metabolic patterns of individual patients result in sulfuric acid eluates ranging from pink to purple, with corresponding differences in wavelength of maximum absorption. The addition of sodium nitrite to these eluates provides a basis of drug evaluation by producing a uniformly absorbing intense purple color with an absorption maximum at 565 millimicron (read in the Beckman DB spectrophotometer). A calibration curve from 0 to 75 microgram of thioridazine was prepared, and absorbance of the unknown is read against this calibration or a similar one to be prepared for the specific spectrophotometer to be used.