Table 3

Comparison of rate of dobutamine infusion at steady state with rates of dobutamine and 3-O-methyldobutamine metabolite elimination in urine of a pediatric patient

	nmol min⁻¹	%^3-a
Intravenous infusion rate
Dobutamine (measured)^3-b	322	100
Dobutamine (prescribed)	309	96
Urinary excretion rates
Dobutamine	3	1
Dobutamine sulfate	52	16
Dobutamine glucuronide	19	6
Dobutamine ⁺conjugates^3-c	106	33
3-O-Methyldobutamine	7	2
3-O-Methyldobutamine sulfate	107	33
3-O-Methyldobutamine glucuronide	8	3
3-O-Methyldobutamine ⁺ its conjugates^3-d	151	47
Sum of dobutamine ⁺ conjugates^3-c and 3-O-methyldobutamine ⁺conjugates^3-d	257	80

See Materials and Methods for description of the 9-year-old, 31-kg male patient, experimental conditions, and analytical methods.

↵3-a Indicated percentages are relative to the measured dobutamine infusion rate set at 100.
↵3-b The measured infusion rate is the product of the analyzed concentration of dobutamine in the infusate (2.078 mg ml⁻¹) and the continuously monitored volume of dobutamine delivered over time (15.4 ml over 330 min). The infusion pump was calibrated to an accuracy of ±3%. Data are converted to nanomoles minute⁻¹.
↵3-c Determined by HPLC as dobutamine after acid hydrolysis of urine.
↵3-d Determined by HPLC as 3-O-methyldobutamine after acid hydrolysis of urine.