Bunorfin is a preparation based on buprenorphine, used in substitution therapy. Buprenorphine is a lipophilic derivative of thebaine (a dimethyl ether of morphine) and is a partial agonist (agonist-antagonist) of the mu receptors. The antagonist action of Bunorfin on the mu and kappa receptors is delayed compared to its agonist action. The drug exhibits a plateau effect (at doses of 8-10 mg), meaning it cannot be overdosed.

It has an affinity for the mu receptors that is 40 times greater than that of morphine. This drug causes euphoric symptoms less frequently and to a lesser extent, has a milder effect on smooth muscle contraction, and has a lower tendency to induce dependence. Substitution therapy with Bunorfin is intended for less dependent patients, particularly those who do not require methadone doses higher than 40 mg per day.

The drug is available in 2 mg and 8 mg tablets. In substitution therapy, the maximum dose usually does not exceed 16 mg. The drug is administered orally, sublingually.