Buprenorfin till get : grundläggande farmakokinetik och påverkan på beteende

Abstract: In this study the opioid buprenorphine was given to 8 clinically healthy goats. The pharmacokinetics and behavioral effects were studied. Injections of buprenorphine, 0.02 mg/kg body weight was given both intramuscularly (i.m.) and intravenously (i.v.) with a cross over design. The results showed a short half-life of the drug in the plasma, 65.9 ± 17.4 min (mean ± SD), after i.v. injection. After i.m. injection no difference in half-life was shown. Total body clearance after the i.m. injection was lower, 58.5 ± 16.6 mL/kg/min, than after the i.v. injection which was 79.7 ± 19.0 mL/kg/min. The volume of distribution (Vdss) was large, 5.04 ± 1.14 L/kg. Bioavailability was complete. Absorption was fast after i.m. injection, Tmax 15.6 ± 11.5 min with Cmax 5.89 ± 2.0 ng/ml. The short half-life makes the drug less desirable if long term analgesia is required because it would have to be administrated several times a day to have a good analgetic effect. The behavioral studies included behaviors such as climbing, active lying, gnawing and ruminating. The results showed that the goats became agitated and that they stopped ruminating for more than 5 hours. The ceasing in rumination is serious and is another factor which makes the drug most unsuitable in goats. In conclusion, if pain control during a longer period is desired, both behavioral and pharmacokinetic results indicate that buprenorphine is not the drug of choice in goats.