Pharmacology · Opioids and antagonists
Buprenorphine !
A high-affinity partial μ agonist with a ceiling on respiratory depression. It treats opioid use disorder and pain; it can precipitate withdrawal.
Updated 2026-11-01
The figure shows morphine, a full agonist, in the μ receptor; buprenorphine occupies the same site. There is no structure of buprenorphine in the receptor.
Mechanism of action
Buprenorphine is a partial μ-receptor agonist: it binds with very high affinity and leaves very slowly, but activates the receptor only partly. So it has a ceiling effect on respiratory depression, displaces full agonists (and can precipitate withdrawal in people using them), and naloxone reverses its established effects only with difficulty. It also acts at κ, δ and nociceptin receptors.
- Binds the μ receptor with high affinity and leaves very slowly
- Activates it only partly: a ceiling effect on breathing
- Displaces full agonists and blocks their effect
- Less craving and withdrawal, with lower overdose risk
Pharmacokinetics
- Absorption
- Sublingual or buccal; swallowed, much of its effect is lost.
- Metabolism
- Liver, with a major role for CYP3A4.
- Onset and duration
- Its clinical effect does not track blood levels because it leaves the receptor slowly; after stopping, withdrawal appears late.
Indications
- Opioid use disorder (induction and maintenance), as part of a plan with psychosocial support
- Pain needing an opioid (injectable and transdermal forms)
Adverse effects
Common
- Headache
- Nausea, vomiting and constipation
- Sweating
- Insomnia
- Withdrawal symptoms at the start
Contraindications
- Hypersensitivity to buprenorphine
Key interactions
- Benzodiazepines, alcohol and other central nervous system depressants
- Add up to profound sedation, respiratory depression, coma and death.
- CYP3A4 inhibitors
- Raise buprenorphine levels.
- Full opioid agonists
- Buprenorphine displaces full agonists and can precipitate withdrawal or weaken their pain relief.
What is monitored
- Objective signs of withdrawal before the first dose
- Liver function tests before and during treatment
- Sedation and breathing, above all with other depressants
- Dental health
Administration and safety
- The tablet is placed under the tongue until it dissolves; it is not cut, chewed or swallowed.
- Nothing is eaten or drunk until it has fully dissolved; then the teeth and gums are rinsed with a sip of water.
- The first dose is given only when clear signs of withdrawal are present, so as not to precipitate it.
- Controlled medicine: the order is verified, every dose recorded and leftovers kept secure.
Nursing care
- Assess withdrawal with an objective scale before starting.
- Teach the sublingual technique and the rinse afterwards because of the risk of tooth decay.
- Keep naloxone available for the patient and family because of the risk of relapse and overdose.
- Watch sedation and breathing, above all if combined with benzodiazepines or alcohol.
- Review liver tests and ask about jaundice or dark urine.
Pregnancy and breastfeeding
It is used in pregnancy to treat opioid use disorder (without naloxone in some regimens); the newborn may develop neonatal opioid withdrawal syndrome.
Test yourself
Think of the answer, then tap the question to see it.
Why does buprenorphine carry less risk of fatal respiratory depression than morphine?
Because it is a partial μ agonist: its effect on breathing has a ceiling even as the dose rises (unless other depressants are added).
Why can buprenorphine precipitate withdrawal, and when is it started to avoid that?
It displaces the full agonist from the receptor and activates it less; it is started only once the patient shows clear signs of withdrawal.
Why does naloxone reverse established buprenorphine effects only with difficulty?
Because of buprenorphine's high affinity and very slow release from the μ receptor.
What dental care is taught with sublingual buprenorphine?
After it dissolves, take a sip of water, swish it around the teeth and gums and swallow, because of reports of severe decay and tooth loss.
Related drugs
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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Buprenorphine Sublingual (opioid dependence): MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); BUPRENORPHINE HYDROCHLORIDE tablet (DailyMed (U.S. National Library of Medicine), 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 23 (McGraw Hill, 2023); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.