Table 1.

Metabolic parameters of morphine in neonates. The figures are means. The adult values are normal and are used for comparison.

Reference	Number of cases	Dose	Developmental stage	Age at treatment	Procedure	Clearance (ml/min/kg)	Notes
8	16	Continuous infusion	7 Preterm 9 Term	NA	Analgesia	NA	Morphine-3 sulfate present in urine Morphine-6 sulfate absent in urine Morphine sulfation negligible in neonates
9	12	Infusion	5 Preterm 7 Term	NA	Analgesia	NA	M-3G present in all patients M-6G present in 10 patients
10	16	Average dose 92±19 µg/kg	Preterm 25-32 weeks g	<5 to 66 days (mean: 10)	Ventilation	NA	M-3G and M-6G found in two thirds of acutely ill preterm newborns
11	49	20 µg/kg/h 30 µg/kg/h	Term	1 day to 2.5 years	Post-surgery	5-21	Morphine sulfate clearance equal to adult values at age 2-25 months
12	17	100-200 µg/kg + infusion	Preterm (26-34 weeks)	1 day	Analgesia	NA	M-3G detected in plasma on day 1 M-6G detected in plasma on day 1
13	10	100 µg/kg	Preterm (25-34 weeks)	1 day	Analgesia	NA	Detected in plasma: Morphine Morphine-3-glucuronide at 2 hours Morphine-6-glucuronide at 24 hours
14	35	Dose adjusted to reach steady state: 20 ng/ml, 7-25 µg/kg/h	Term	1-7 days 8-90 days 91-180 days 180-380 days	Before and after cardiac surgery	9.2-48.9 before surgery 5.5-21.7 after surgery	M-3G detected from day 1 2 hours after dosing M-6G detected from day 2
15	31	Dose adjusted through effect	Preterm Term	10 days	Ventilation	Increase from 0.8-6.5	To provide a rational basis for morphine administration
16	68	10 µg/kg/h	Term	<7 days (52) >7 days (16)	Major surgery	NA	To determine age-related differences in morphine needs

M-3G: Morphine-3-glucuronide; M-6G: Morphine-6-glucuronide.