The impact of hemolysis on stability of -desethyloxybutynin in human plasma.

Stability must be evaluated before quantitation of drugs or metabolites concentrations in biological matrices. We reported a case study where instability of a drug metabolite was mediated by hemolysis. The instability of both enantiomers of -desethyloxybutynin was observed in hemolyzed plasma stored at -20°C. The investigations indicated that heme-mediated oxidation converted the metabolite to its -oxide. Storing samples under lower temperature (-50°C or below) or treatment with the antioxidant ascorbic acid stabilized the metabolite. The evaluation of the stability of some analytes in a hemolyzed sample is crucial as it may negatively impact incurred sample reanalysis or pharmacokinetic profiles on highly hemolyzed samples.