Pharmacokinetics of Bupivacaine in Chickens (Gallus gallus domesticus) During Isoflurane Anesthesia

). Bupivacaine is an amide local anesthetic that works by blocking sodium channels and is 4 times as potent as lidocaine. Though bupivacaine is not recommended for intravenous injection, the purpose of this study was to mimic an accidental intravenous injection. A single dose of preservative-free bupivacaine at 2 mg/kg was administered intravenously over 20 seconds in 6 healthy layer chickens weighing 1340 6 193.4 grams. Each hen was placed under isoflurane anesthesia and intubated prior to drug administration. Blood was collected at baseline once under anesthesia and then at 1, 2, 5, 10, 15, 30, 60, 90, 120, 180, and 240 minutes postdrug administration. Vitals were monitored routinely and recorded. Each patient recovered without any complications. Plasma was separated and immediately frozen at -808C (-1128F) until it was assayed for bupivacaine by high-performance liquid chromatography. A 2-compartment model was used to estimate pharmacokinetic parameters, including clearance (median 59.2, range 43.2-77.1 mL/min/kg), terminal half-life (median 18.2, range 12.4-36.4 min), apparent volume of distribution at steady state (median 1571.7, range 961.6-2113.4 mL/kg), area under the curve (median 33.9, range 26.0-46.3 min*mg/mL), and mean residence time (median 24.3, range 15.1-48.9 min). These results describe the pharmacokinetics of bupivacaine in healthy laying hens anesthetized with isoflurane and can be used in the creation of future experimental designs of the use of bupivacaine in this species.