Table 2

Steady-state metoprolol, α-hydroxymetoprolol, and O-demethylmetoprolol concentrations (mean ± SD, μM) in the effluent at each concentration

	Pre-Amino Acids	Amino Acids	Post-Amino Acids
3.74 μM metoprolol inlet concentration
Metoprolol^2-a	0.97 ± 0.19	1.94 ± 0.26^2-b	1.16 ± 0.30^2-c
α-Hydroxymetoprolol^2-a	1.45 ± 0.07	1.02 ± 0.18^2-b	1.38 ± 0.18^2-c
O-Demethylmetoprolol	0.28 ± 0.04	0.28 ± 0.04	0.32 ± 0.04
4.49 μM metoprolol inlet concentration
Metoprolol^2-a	1.23 ± 0.15	2.40 ± 0.19^2-b	1.46 ± 0.19^2-c
α-Hydroxymetoprolol^2-a	1.73 ± 0.04	1.27 ± 0.18^2-b	1.69 ± 0.21
O-Demethylmetoprolol^2-a	0.43 ± 0.04	0.36 ± 0.08^2-b	0.47 ± 0.04^2-c
5.61 μM metoprolol inlet concentration
Metoprolol^2-a	1.68 ± 0.56	3.00 ± 0.90^2-b	2.09 ± 0.56^2-b
α-Hydroxymetoprolol^2-a	2.18 ± 0.42	1.59 ± 0.53^2-b	1.98 ± 0.42^2-b
O-Demethylmetoprolol	0.43 ± 0.08	0.40 ± 0.08	0.47 ± 0.12
7.48 μM metoprolol inlet concentration
Metoprolol^2-a	2.88 ± 0.52	4.71 ± 0.37^2-b	3.14 ± 0.45^2-b ^, ^2-c
α-Hydroxymetoprolol^2-a	2.82 ± 0.32	1.80 ± 0.25^2-b	2.61 ± 0.28^2-b ^, ^2-c
O-Demethylmetoprolol^2-a	0.59 ± 0.08	0.43 ± 0.08^2-b	0.63 ± 0.08^2-c
18.7 μM metoprolol inlet concentration
Metoprolol^2-a	11.2 ± 1.38	15.2 ± 0.75^2-b	12.0 ± 0.82^2-c
α-Hydroxymetoprolol^2-a	4.27 ± 0.46	1.98 ± 0.25^2-b	3.53 ± 0.42^2-b ^, ^2-c
O-Demethylmetoprolol^2-a	1.07 ± 0.12	0.63 ± 0.08^2-b	1.07 ± 0.08^2-c
44.9 μM metoprolol inlet concentration
Metoprolol^2-a	32.2 ± 1.8	39.6 ± 1.1^2-b	34.7 ± 1.9^2-c
α-Hydroxymetoprolol^2-a	6.81 ± 0.99	3.46 ± 0.67^2-b	5.54 ± 1.3^2-b ^, ^2-c
O-Demethylmetoprolol^2-a	2.17 ± 0.20	1.11 ± 0.12^2-b	2.09 ± 0.24^2-c

↵2-a p < 0.05 in the repeated-measures ANOVA.
↵2-b p < 0.05, Pre-amino acidsvs. Amino Acids and Pre-Amino Acids vs.Post-Amino Acids by paired t test.
↵2-c p < 0.05, Amino Acidsvs. Post-Amino Acids by paired t test.