The absorption of medetomidine released by continuous infusion from an osmotic pump in the abdominal cavity was studied in pregnant sheep during the 24 h postoperative period. Additionally pain and sedation was assessed. Eleven sheep were studied: six were treated with a medetomidine loaded osmotic pump delivering 10 microL/h (3 microg/kg/h medetomidine); and five with a saline loaded osmotic pump (control). Serial blood samples were taken and analysed to determine plasma medetomidine levels. Medetomidine was absorbed from the peritoneal cavity and a steady plasma concentration was achieved within 10 h, mean (SD) peak concentration was 2.87 (0.22) ng/mL. Sheep receiving medetomidine analgesia had significantly lower pain scores at 10 h than controls. Four control sheep required rescue analgesia, compared with 0 in the treatment group. Delivery of 3 microg/kg/h medetomidine by an intraperitoneal osmotic pump to pregnant sheep in the 24 h postoperative period provides adequate plasma concentrations of medetomidine for analgesia without sedation.
Murdoch, F. R., Maker, G. L., Nitsos, I., Polglase, G., & Musk, G. C. (2013). Intraperitoneal medetomidine: a novel analgesic strategy for postoperative pain management in pregnant sheep. Laboratory Animals, 47(1), 66 - 70. https://doi.org/10.1177/0023677212473712