MATERNAL AND FETAL BUPRENORPHINE PHARMACOKINETICS IN PREGNANT SHEEP DURING TRANSDERMAL PATCH DOSING

Buprenorphine is used in the opioid maintenance treatment for dependent patients, including pregnant women. Despite wide use, limited data exists on buprenorphine pharmacokinetics and fetal exposure during pregnancy. The aim of our study was to determine transdermal patch dosing sheep and, extent transplacental transfer fetus. Pregnant late gestation (n=50) received 20, 25 or 40 µg/h as a 7-day extended-release patch. Plasma samples were collected from ewe fetus days 1 – 6, norbuprenorphine concentrations determined. During period had surgical procedure second day, recovery phase, an experimental sixth day. In experiment, hypoxia induced under anesthesia 18 investigate if decreased pH would cause ion-trapping fetal/maternal plasma concentration ratio determined day at baseline hypoxia. Maternal modelled with population pharmacokinetic method using this previous intravenous administration study. provided extended release throughout period, but rate declined approximately 20 h after placement. median 13 27 % baseline. A over 100 observed four (102 269 %). minor increase seen fetal/maternal-ratios maternal Norbuprenorphine undetected all samples. low passage less than one fourth ewe's supports alternative methadone therapy