Mari Kinnunen1, Hannu Kokki1, Heidi Hautajärvi2, Heikki Huhta3, Veli-Pekka Ranta4, Juha Räsänen5, Hanna-Marja Voipio6, Merja Kokki7. 1. School of Medicine, University of Eastern Finland, Kuopio, Finland. 2. Admescope Ltd, Oulu, Finland. 3. Department of Surgery, University of Oulu, Oulu, Finland. 4. School of Pharmacy, University of Eastern Finland, Kuopio, Finland. 5. Department of Obstetrics and Gynecology, Helsinki University Hospital, Helsinki, Finland. 6. Laboratory Animal Center, Department of Experimental Surgery, University of Oulu and Oulu University Hospital, Oulu, Finland. 7. Department of Anesthesia and Operative Services, Kuopio University Hospital, Kuopio, Finland.
Abstract
INTRODUCTION: There are limited data on oxycodone pharmacokinetics during pregnancy and on fetal exposure after maternal administration. The present study describes the pharmacokinetics of intravenous (i.v.) oxycodone in pregnant sheep and fetal exposure after intravenous and epidural administration. MATERIAL AND METHODS: Ten pregnant sheep received 0.1 mg·kg-1 oxycodone intravenously, and blood samples were collected up to 24 hours. Seven days later, the ewes were randomized to receive 0.5 mg·kg-1 oxycodone intravenously (n = 5) or epidurally (n = 5) as a single bolus, before laparotomy for placement of catheters into the fetal superior vena cava and carotid artery. Paired maternal and fetal blood samples were taken when the fetal arterial catheter was in place and at the end of surgery. Maternal blood samples were taken up to 24 hours. RESULTS: After 0.1 mg·kg-1 oxycodone intravenously, the median clearance was 5.2 L·h-1 ·kg-1 (range 4.6-6.2), but the volume of distribution varied between 1.5 and 4.7 L·kg-1 . The area under the curve was 17 h·ng·mL-1 (range 14-19) and the plasma concentration at 2 minutes 60 ng·mL-1 (range 50-74). Following administration of 0.5 mg·kg-1 intravenously or epidurally, oxycodone concentrations were similar in the maternal and the fetal plasma. Accumulation of oxymorphone in the fetus occurred; fetal-to-maternal ratios were 1.3-3.5 (median 2.1) in the i.v.-group and 0.9-3.0 (1.3) in the Epidural-group. CONCLUSIONS: We determined the pharmacokinetics of oxycodone in pregnant sheep. We showed accumulation of oxymorphone, which an active metabolite of oxycodone, in the fetus. Further studies in human pregnancies are required to evaluate the safety of oxycodone.
INTRODUCTION: There are limited data on oxycodone pharmacokinetics during pregnancy and on fetal exposure after maternal administration. The present study describes the pharmacokinetics of intravenous (i.v.) oxycodone in pregnant sheep and fetal exposure after intravenous and epidural administration. MATERIAL AND METHODS: Ten pregnant sheep received 0.1 mg·kg-1 oxycodone intravenously, and blood samples were collected up to 24 hours. Seven days later, the ewes were randomized to receive 0.5 mg·kg-1 oxycodone intravenously (n = 5) or epidurally (n = 5) as a single bolus, before laparotomy for placement of catheters into the fetal superior vena cava and carotid artery. Paired maternal and fetal blood samples were taken when the fetal arterial catheter was in place and at the end of surgery. Maternal blood samples were taken up to 24 hours. RESULTS: After 0.1 mg·kg-1 oxycodone intravenously, the median clearance was 5.2 L·h-1 ·kg-1 (range 4.6-6.2), but the volume of distribution varied between 1.5 and 4.7 L·kg-1 . The area under the curve was 17 h·ng·mL-1 (range 14-19) and the plasma concentration at 2 minutes 60 ng·mL-1 (range 50-74). Following administration of 0.5 mg·kg-1 intravenously or epidurally, oxycodone concentrations were similar in the maternal and the fetal plasma. Accumulation of oxymorphone in the fetus occurred; fetal-to-maternal ratios were 1.3-3.5 (median 2.1) in the i.v.-group and 0.9-3.0 (1.3) in the Epidural-group. CONCLUSIONS: We determined the pharmacokinetics of oxycodone in pregnant sheep. We showed accumulation of oxymorphone, which an active metabolite of oxycodone, in the fetus. Further studies in human pregnancies are required to evaluate the safety of oxycodone.