Abstract: Aim Pharmcokinetic action of MTX and the relationship of drug concentration in cancers with that in the systemic blood were studied. Methods MTX in a dose of 30 mg/m² was given to 31 cancer patients. Samples of systemic blood were taken at 1h, 3h, 6h, 12h, 24h, 30h, and 48h after drug administration. The same dosage of MTX was given to 30 patients with mammary cancer 3 hours before operation and blood samples from the organ where the cancer was located and from peripheral veins were taken during operation. The drug concentration in each kind of samples was detected and analysed. Results The plasma concentration vs time date were better described by an open three compartment model. In patients with 30 mg/m²,local and systemic drug concentrations were in high relationship, and adverse drug reactions were smaller than that of other dose. Conclusion The 30mg/m2 dose of MTX was a safe therapeutic dose.

Key words: MTX, Pharmacokinetics, Drug concentration