Pharmacodynamic properties
Buprenorphine is a potent, long-acting analgesic acting at opiate receptors in the central nervous system. Buprenorphine can potentiate the effects of other centrally-acting agents, but has, at clinical doses, only a limited sedative effect of its own. Buprenorphine exerts its analgesic effect via high affinity binding to opiate receptors, particularly µ, in the central nervous system. At clinical dose levels, buprenorphine binds with high affinity and high receptor avidity, such that its dissociation from the receptor site is slow. This could account for its longer duration of activity. Buprenorphine has little effect on gastro-intestinal motility.
Pharmacokinetic particulars
Signs of sedation normally appear by 15 minutes. Analgesic effects appear around 30 minutes with peak effects usually being observed at about 1 – 1.5 hours. Following intravenous administration to dogs there is considerable inter-dog variability in pharmacokinetic parameters. The major route of excretion in all species is the faeces. Highest concentrations of drug-related material were observed in liver, lung and brain. Peak levels occurred rapidly and declined to low levels by 24 hours after dosing.