DBS sampling in imatinib therapeutic drug monitoring: from method development to clinical application.

BACKGROUND: Imatinib (IM) is widely used in treatment of chronic myeloid leukemia with target trough plasma concentrations above 1000 ng ml(-1). DBS can increase access to IM therapeutic drug monitoring. RESULTS: IM was measured in the range 50-4000 ng ml(-1) by UHPLC-MS/MS using one 6 mm DBS in a fully validated method. IM was stable at DBS maintained at 40°C for 36 days. Plasma and DBS concentrations were highly correlated (r > 0.96). The use of a IM concentration target of 765 ng ml(-1) in DBS identified 93% of patients with plasma concentration below 1000 ng ml(-1). CONCLUSION: IM can be measured in DBS using UHPLC-MS/MS with results comparable to those obtained in blood plasma.