title: Intravenous oxycodone for pain relief in the first stage of labour--maternal pharmacokinetics and neonatal exposure.
abstract: Physiological changes during pregnancy may change pharmacokinetics of compounds. Oxycodone is an increasingly used opioid agonist in acute pain management but its pharmacokinetics in labouring women has not been established. We studied the maternal pharmacokinetics and neonatal exposure of intravenous oxycodone for pain relief in the first stage of labour. The study was prospective, open-labelled and with a control group. After informed consent, 15 nulliparous parturients and newborns, and newborns in a control group were studied. In the study group, oxycodone boluses of 1 mg i.v., up to a cumulative dose of 5 mg, was administered when labour pain score was 5/10 or higher. As the control group, 30 other newborns after uncomplicated deliveries with no systemic opioids were assessed for the neonatal outcome. In the study group, maternal pharmacokinetics of oxycodone was measured from plasma concentrations during labour, and neonatal exposure was assessed from umbilical plasma samples using population pharmacokinetic methods. Maternal plasma oxycodone concentration decreased with a median half-life of 2.6 hr (range, 1.8-2.8). Oxycodone concentrations in the umbilical plasma 2.7 μg/l (0.3-14.5) were similar as in maternal plasma 2.4 (0.1-14.8) μg/l at the time of birth. No severe or unexpected adverse effects were noted. To conclude, firstly, maternal elimination half-life of i.v. oxycodone was significantly shorter than that reported in non-pregnant women, and secondly, maternal plasma oxycodone at the birth correlated well with neonatal umbilical concentrations and may, thus, be used as an estimate of neonatal exposure.
authors.affiliation: Department of Anaesthesia and Operative Services, Kuopio University Hospital and School of Medicine, University of Eastern Finland, Kuopio, Finland. merja.kokki@kuh.fi
authors.forename: Merja
authors.initials: M
authors.lastname: Kokki
authors.forename: Maria Gonzalez
authors.initials: MG
authors.lastname: Franco
authors.forename: Kaisa
authors.initials: K
authors.lastname: Raatikainen
authors.forename: Pyry
authors.initials: P
authors.lastname: Välitalo
authors.forename: Ulla
authors.initials: U
authors.lastname: Sankilampi
authors.forename: Seppo
authors.initials: S
authors.lastname: Heinonen
authors.forename: Pertti J
authors.initials: PJ
authors.lastname: Neuvonen
authors.forename: Hannu
authors.initials: H
authors.lastname: Kokki
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006207:Half-Life; D006801:Humans; D007231:Infant, Newborn; D007275:Injections, Intravenous; D007743:Labor, Obstetric / Q000187:drug effects*; D018811:Maternal Exposure; D010098:Oxycodone / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D010146:Pain / Q000188:drug therapy*; D010865:Pilot Projects; D011247:Pregnancy; D055815:Young Adult
chemical_list: D010098:Oxycodone