Pharmacokinetics of butorphanol tartrate in rabbits.

The pharmacokinetic properties of butorphanol tartrate were determined in 7 rabbits after IV and SC injection (0.5 mg/kg of body weight). A 2-compartment model (biexponential) best represented the concentration vs time curve after IV injection. The half-life was calculated to be 1.64 hours via IV administration, whereas SC injection resulted in an elimination half-life of 3.16 hours.