BUPRENORPHINE
Clinical safety rating: caution
Benzodiazepines and other CNS depressants increase risk of respiratory depression Can precipitate withdrawal in patients dependent on other opioids.
Partial mu-opioid receptor agonist and weak kappa-opioid receptor antagonist; also exhibits high affinity but low intrinsic activity at mu-opioid receptors, producing analgesia and euphoria with a ceiling effect on respiratory depression.
| Metabolism | Primarily hepatic via N-dealkylation to norbuprenorphine via CYP3A4, with minor contribution from CYP2C8; norbuprenorphine is active and further glucuronidated; undergoes extensive first-pass metabolism; mainly excreted in feces (as unchanged drug and metabolites) and to a lesser extent in urine. |
| Excretion | Buprenorphine is primarily eliminated via biliary excretion of its metabolites, with approximately 70% of the dose recovered in feces as unchanged drug and metabolites. Renal elimination accounts for about 10-30%, primarily as metabolites. |
| Half-life | Terminal elimination half-life is 24-60 hours (mean ~37 hours) due to enterohepatic recirculation and slow dissociation from mu-opioid receptors. Clinically, this allows for every-other-day or thrice-weekly dosing in maintenance therapy. |
| Protein binding | Approximately 96% bound to alpha- and beta-globulins, with minimal binding to albumin. |
| Volume of Distribution | Volume of distribution is 2-4 L/kg (mean ~3.2 L/kg). High Vd indicates extensive tissue distribution, including sequestration in brain and adipose tissue. |
| Bioavailability | Sublingual: 30-55% (variable due to first-pass metabolism); Oral: ~15% (low due to extensive hepatic metabolism); Transdermal: ~15-20%; Intravenous/Intramuscular: 100%. |
| Onset of Action | Sublingual: 15-30 minutes; Intravenous: within minutes; Intramuscular: 10-15 minutes; Transdermal: 12-24 hours (steady state reached in ~3 days). |
| Duration of Action | Sublingual: 6-8 hours (analgesic) but up to 24-72 hours for opioid receptor blockade due to slow dissociation; Transdermal: 7 days; Intravenous: 4-6 hours. Duration is dose-dependent and prolonged at higher doses. |
| Molecular Weight | 504.4 |
Sublingual tablet: 2-8 mg every 6-8 hours as needed for pain; for opioid use disorder: 12-16 mg once daily. Transdermal patch: 5-20 mcg/h applied every 7 days. IV/IM: 0.3 mg every 6-8 hours.
| Dosage form | FILM, EXTENDED RELEASE |
| Renal impairment | No dosage adjustment required for mild to moderate impairment (GFR >30 mL/min). For severe impairment (GFR <30 mL/min), consider reducing dose and increasing interval; avoid in anuric patients. |
| Liver impairment | Child-Pugh A: no adjustment. Child-Pugh B: reduce dose by 50% and monitor. Child-Pugh C: contraindicated or use with extreme caution with significant dose reduction (e.g., 50-75% reduction). |
| Pediatric use | For pain (≥2 years): sublingual tablet 2-6 mcg/kg every 4-8 hours; IV/IM 2-6 mcg/kg every 4-6 hours. For opioid use disorder (≥16 years): induction 2-4 mg, then titration to 12-16 mg once daily; safety in <16 years not established. |
| Geriatric use | Initiate at lowest dose (e.g., sublingual 2 mg, transdermal 5 mcg/h) and titrate slowly due to increased sensitivity and risk of respiratory depression, falls, and cognitive impairment; monitor renal and hepatic function. |
| 1st trimester | Limited human data; animal studies show increased risk of neural tube defects at high doses. Use only if benefit outweighs risk. |
| 2nd trimester | May cause fetal dependence and neonatal withdrawal syndrome. Use only if clearly needed. |
| 3rd trimester | Chronic use can lead to neonatal opioid withdrawal syndrome (NOWS); monitor newborn. Avoid prolonged use near term. |
Clinical note
Benzodiazepines and other CNS depressants increase risk of respiratory depression Can precipitate withdrawal in patients dependent on other opioids.
| FDA category | Animal |
| Placental transfer | Crosses placenta; rapid equilibration with fetal plasma. Fetal/maternal ratio ~0.6-1.0. |
| Breastfeeding |
■ FDA Black Box Warning
Risk of respiratory depression, particularly in non-opioid-tolerant patients; risk of neonatal opioid withdrawal syndrome with prolonged use during pregnancy; risk of serious harm or death with concomitant use of benzodiazepines or CNS depressants; requirement for patient access to emergency medical services and monitoring; risk of addiction, abuse, and misuse; risk of accidental exposure.
| Common Effects | opioid use disorder |
| Serious Effects |
Hypersensitivity to buprenorphine or any component of the formulationSevere respiratory insufficiencySevere hepatic impairment (Child-Pugh class C)Acute alcoholism or delirium tremensPatients currently on full opioid agonists (e.g., morphine, methadone) without detoxification (risk of precipitated withdrawal)
| Precautions | Respiratory depression: ceiling effect exists, but risk increases with non-opioid-tolerant use or coadministration of CNS depressants, Potentiation of respiratory depression by benzodiazepines and alcohol, Neonatal opioid withdrawal syndrome: avoid prolonged use during pregnancy unless necessary, Adrenal insufficiency: risk with prolonged use, Androgen deficiency: may occur with chronic use, Hypotension, especially in hypovolemic patients, Biliary tract spasm: may cause constriction of sphincter of Oddi, Risk of misuse, abuse, and diversion |
Loading safety data…
| Buprenorphine is excreted into breast milk in low concentrations. Monitor infant for sedation, respiratory depression, and withdrawal. Generally considered compatible with breastfeeding in mothers on stable maintenance therapy, but weigh risks and benefits. |
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | FDA Pregnancy Category C. First trimester: No clear evidence of major malformations in human studies, but animal studies show increased risk of neural tube defects and skeletal anomalies at high doses. Second and third trimesters: Risk of neonatal opioid withdrawal syndrome (NOWS) with chronic use; may cause fetal respiratory depression if used near term. |
| Fetal Monitoring | Maternal: Respiratory rate, sedation level, blood pressure, heart rate, signs of withdrawal or misuse. Fetal: Ultrasound for fetal growth and anatomy (especially if used in first trimester), fetal heart rate monitoring during third trimester, and assessment for NOWS at delivery. Regular monitoring of liver function tests due to potential hepatotoxicity. |
| Fertility Effects | Limited human data. In animal studies, buprenorphine at high doses impaired fertility and caused reduced pregnancy rates and increased preimplantation loss. In humans, chronic opioid use may disrupt menstrual cycles and reduce fertility via hypothalamic-pituitary-gonadal axis suppression; effects likely reversible upon discontinuation. |
| Food/Dietary | No specific food interactions. Grapefruit juice may increase buprenorphine levels via CYP3A4 inhibition. Avoid excessive alcohol. Maintain a balanced diet to support overall health during treatment. |
| Clinical Pearls | Buprenorphine is a partial mu-opioid agonist with a ceiling effect on respiratory depression, making it safer than full agonists in overdose. It has high affinity for mu receptors, which can precipitate withdrawal if given to opioid-dependent patients already on full agonists. Sublingual administration avoids first-pass metabolism. Monitor liver function due to hepatotoxicity risk, especially with injectable forms. Long half-life allows every-other-day dosing in maintenance therapy. Naloxone is added in combination products to deter intravenous abuse. |
| Patient Advice | Take buprenorphine exactly as prescribed; do not increase dose or frequency without consulting your doctor. · Do not use alcohol, benzodiazepines, or other sedatives while on buprenorphine as it can cause severe drowsiness, respiratory depression, or coma. · Avoid driving or operating heavy machinery until you know how buprenorphine affects you. · Do not stop abruptly; withdrawal symptoms may occur. Taper under medical supervision. · Store safely out of reach of children; accidental ingestion can be fatal. · Inform your doctor if you have liver disease, breathing problems, or are pregnant. · If you miss a dose, take it as soon as possible; skip if almost time for next dose. Do not double dose. |