Optimizing the Use of Morphine in Pre-Term Neonates

The investigators hypothesize that identifying co-variates predictive of variability in morphine disposition and/or response will provide the scientific basis for rationale and individualized morphine dosing schemes in neonates and young infants.

60 preterm neonates ranging in gestational age from 22 to 32 weeks will be recruited from the NICU. Stratification by gestational age will be done to ensure broad representation. The decision to initiate morphine therapy will be based solely on clinical indications. Prior to morphine dosing, a biochemical assessment of hepatic and renal function will be obtained. A 0.05 mg/kg loading dose of morphine will be given by an intravenous infusion over 30-minutes in preterm neonates with a gestational age of less than 29 weeks, followed by a continuous infusion of 0.005 mg/kg/h, whereas a loading dose of 0.1 mg/kg will be given in preterm neonates with a gestational age of 29 weeks or more followed by a continuous infusion of 0.01 mg/kg/h. Pain assessment will be performed at baseline (prior to study medication administration) and at .5, 1, 2, 4, 8, 12 and 24 hours after the dose. At each of these time points infants will be videotaped for two minutes with two cameras. Videotapes will be scored afterward using standard validated pain assessment tools for preterm infants.

Inclusion criteria

• Preterm neonates of both genders and all races
• postnatal age less than 30 days
• an indwelling (peripheral or umbilical) arterial line, and
• a clinical indication for intravenous morphine administration

Exclusion criteria

• Neonates with severe asphyxia, grade III or IV intraventricular hemorrhage, major congenital malformations/facial malformations, neurological disorders, and those receiving continuous or intermittent neuromuscular blockers.
• clinical or biochemical evidence of hepatic and renal compromise (including systemic hypoperfusion) or
• received drugs that are UGT2B7 substrates (including Lorazepam, ibuprofen, valproic acid, naloxone and other morphine derivatives or propanolol)