Stability of suramin in aqueous solution; possible implications for the search for suramin metabolites in patients

The stability of an aqueous solution of suramin has been determined. The only degradation product detectable by HPLC was the amine precursor 2. The decomposition kinetics of suramin at different temperatures are shown. Because of first order kinetics the Arrhenius equation could not be used to evaluate the decomposition data. A good correlation was obtained between the reaction constants and the temperature (r = 0.9898). After 42 days at 37 degrees C, 2 % of suramin are hydrolysed. Possible implications of our results for the search for suramin metabolites in patients are discussed.