Why monitor blood levels of imatinib?
Trough plasma levels of imatinib have been associated with both cytogenetic and molecular responses, with a level of around 1000 ng/mL recommended for a full molecular response.1 However, at a given dose, trough plasma levels of imatinib may vary greatly between patients. There are several potential causes, including pharmacokinetic factors such as drug–drug interactions, and patient-related factors such as adherence. Hence, if a patient is not responding to imatinib as expected, blood-level testing is an essential tool for determining whether imatinib blood levels are adequate. It should not be assumed that the patient has become resistant to imatinib.
