Beta-endorphin concentration after administration of sucrose in preterm infants.

BACKGROUND Sucrose is an effective analgesic for procedural pain in preterm infants. It has been hypothesized that its analgesic effects are mediated by the release of endogenous opioid neurotransmitters such as beta-endorphin. OBJECTIVE To determine whether intraoral administration of sucrose was associated with an increase in serum beta-endorphin concentrations in preterm infants with a gestation period less than 29 weeks who were not exposed to a painful stimulus. METHODS We performed a prospective open-label study in preterm infants admitted to 2 tertiary neonatal intensive care units. Each infant received a single dose of 30% sucrose intraorally during a 1- to 2-minute period. A blood sample was obtained using an indwelling arterial catheter to determine beta-endorphin concentration immediately before and 2 to 5 minutes after the commencement of sucrose administration. RESULTS We enrolled 11 preterm infants with a mean +/- SD gestational age of 27.2 +/- 0.9 weeks and a mean +/- SD birth weight of 1018 +/- 238 g (1.02 +/- 0.24 kg) at a mean +/- SD postnatal age of 3.0 +/- 2.5 days. The mean +/- SD beta-endorphin concentration before and after sucrose administration was 60.4 +/- 30.5 pg/mL and 57.4 +/- 22.4 pg/mL, respectively (P =.45). No adverse events were observed during the study procedures. CONCLUSION Intraoral administration of sucrose in preterm infants did not lead to an increase in serum beta-endorphin concentrations at a point in time when the analgesic effects of sucrose were presumed to be present.