Table 4.

Stability results for asenapine under different conditions (n = 6).

Storage condition	Quality control level (ng/mL)	In absence of metabolites			In presence of metabolites (20.0 ng/mL of DMA and ASG)
		Mean stability sample (ng/mL)	CV (%)	Change (%)	Mean stability sample (ng/mL)	CV (%)	Change (%)
Bench top stability (24 h, 25 °C)	0.150	0.138	2.4	− 8.0	0.155	2.3	3.3
	15.00	13.62	1.1	− 9.2	14.44	1.4	− 3.7
Freeze-thaw stability (6 cycles, −20 °C)	0.150	0.140	2.8	− 6.9	0.154	3.0	3.1
	15.00	13.93	2.3	− 7.1	14.49	1.2	− 3.4
Auto sampler stability (94 h, 5 °C)	0.150	0.141	4.6	− 6.1	0.143	4.3	− 2.3
	15.00	13.89	2.2	− 7.4	14.01	2.7	− 3.6
Processed sample stability (75 h, 25 °C)	0.150	0.138	2.6	− 8.0	0.139	3.2	− 4.1
	15.00	13.38	1.2	− 10.8	13.94	4.7	− 5.3
Long-term stability (126 days, −20 °C)	0.150	0.139	2.9	− 7.7	–	–	–
	15.00	14.05	0.8	− 6.3	–	–	–
Long-term stability (126 days, −70 °C)	0.150	0.137	4.7	− 8.4	–	–	–
	15.00	14.25	3.9	− 5.0	–	–	–

CV: coefficient of variation; DMA: N-desmethyl asenapine; ASG: asenapine N-glucuronide. $\mathrm{Change}\left(\%\right)=\frac{\mathrm{Mean}\mathrm{stability}samples–\mathrm{Mean}\mathrm{comparison}samples}{\mathrm{Mean}\mathrm{comparison}\mathrm{samples}}\times 100.$