Simultaneous Quantification of Methotrexate and Its Metabolite 7-Hydroxy-Methotrexate in Human Plasma for Therapeutic Drug Monitoring

Table 2

Linearity regression parameters for MTX and 7-OH-MTX (n=5).

Analyte	Linearity Range; (ng/mL)	Calibration curve	r	LLOQ; (ng/mL)	Measured Concentration; (ng/mL)	Accuracy; (RE/%)
MTX	5~10000	y=11.4356x-0.0158	0.9977	5	5.23 ± 0.21	4.57
7-OH-MTX	5~10000	y=3.9966x+0.0028	0.9978	5	5.12 ± 0.56	2.35

RE is expressed as [(mean measured concentration)/(nominal concentration)-1]×100%