A recent study demonstrated that trough (sample taken just before the next dose) imatinib plasma concentrations were associated with cytogenetic and molecular response in CML. A patient with trough imatinib plasma concentration >1000 ng/ml is 8 times more likely to experience a therapeutic effect compared with patients who have concentrations below this effect target. Furthermore,GIST patients with a trough imatinib plasma concentration <1100 ug/L had lower rates of clinical benifit and faster time to progression. A target for toxicity has not been defined;however,fluid retension,rash,myalgia and anaemia apper to be common at higher imatinib concentrations.
Suggested target for effect in CML is >1000 ug/L
Suggested target for effect in GIST is >1100 ug/L
Toxicity: monitor patient carefully if trough imatinib plasma concentration exceeds 2000 ug/L