High-performance liquid chromatographic assay for methylglyoxal bis(guanylhydrazone) (methyl GAG) in plasma and urine

A clinically useful analytical method is described for monitoring both plasma and urine levels of methylglyoxal bis(guanylhydrazone) administered in the clinical management of certain neoplasms. The drug is initially separated from the biological matrix by retention on a small (2 cm) column packed with weak cation-exchange resin. The analyte is subsequently eluted quantitatively from the column with hydrochloric acid, and then separated and quantitated by paired ion high-performance liquid chromatography on an RP-18 column. The drug is detected to levels of 50 ng/ml of biological fluid by monitoring the column effluent spectrophotometrically at 280 nm. Absorbance was linearly related to drug concentration over the range 50 ng-50 microgram/ml of plasma or urine, and measurements could be made with a precision of +/- 4% over this range.