Temgesic Mechanism of Action





Agencia Lei Va Hong
Full Prescribing Info
Ampoule: Pharmacology: Pharmacodynamics: Buprenorphine hydrochloride, the active ingredient in Temgesic Injection is a potent, long-acting analgesic. Buprenorphine is a μ (mu) opioid partial agonist and k (kappa) antagonist. It is a strong analgesic of the partial agonist (mixed agonist/antagonist) class. Buprenorphine is approximately 30 times more potent than morphine, and at therapeutically equivalent doses, has a similar onset of action and quality of analgesia, but a longer duration of action.
Pharmacokinetics: Buprenorphine is readily available by i.v. or i.m. routes; the relative bioavailability i.m. to i.v. was 1.07. Peak plasma levels are achieved within a few minutes of i.m. administration and after 10 minutes are not significantly different from those observed after the same dose given i.v.
Buprenorphine is oxidatively metabolised by 14-N-dealkylation to N-desalkyl-buprenorphine (also known as norbuprenorphine) via cytochrome P450 CYP3A4 and by glucuroconjungation of the parent molecule and the dealkylated metabolite. Norbuprenorphine is a μ (mu) agonist with weak intrinsic activity.
Elimination of buprenorphine is bi- or tri exponential, with a long terminal elimination phase 20 to 25 hours, due in part to reabsorption of buprenorphine after intestinal hydrolysis of the conjugated derivative, and in part to the highly lipophilic nature of the molecule.
Buprenorphine is essentially eliminated in the faeces by biliary excretion of the glucuroconjugated metabolites (80 %), the rest being eliminated in the urine.
Toxicology: Preclinical safety data: No preclinical findings of relevance to the prescriber have been reported.
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