Table 2.

Stability of methotrexate in rat plasma (n = 3).

	Spiked concentration (µg/ml)	Three freeze–thaw cycles stability		24 h at room temperature		Stability for 14 d at −80 °C
		RE%	RSD%	RE%	RSD%	RE%	RSD%
Methotrexate	1.0 × 10−1	−9.2	6.8	−6.4	7.2	−3.5	4.1
	4.0	−4.8	5.9	−4.4	4.5	−5.2	6.3
	80.0	−3.0	2.8	2.7	3.8	−1.7	3.5