BUPRENORPHINE HYDROCHLORIDE AND NALOXONE HYDROCHLORIDE
Clinical safety rating: safe
No significant drug interactions Can precipitate acute withdrawal in patients dependent on opioids.
Buprenorphine is a partial mu-opioid receptor agonist and a weak kappa-opioid receptor antagonist; naloxone is a mu-opioid receptor antagonist that is added to deter intravenous abuse.
| Metabolism | Buprenorphine is primarily metabolized by CYP3A4 to norbuprenorphine; naloxone is metabolized by UDP-glucuronosyltransferases (UGT1A1, UGT1A3). |
| Excretion | Buprenorphine: ~70% fecal via biliary excretion, ~30% renal as unchanged drug and metabolites. Naloxone: primarily hepatic metabolism, ~50% renal excretion of metabolites within 6h. |
| Half-life | Buprenorphine: terminal half-life 24-60 hours (mean ~37h) due to slow dissociation from mu-opioid receptors; naloxone: ~2-12 hours (mean ~1-2h IV, slightly longer sublingual). |
| Protein binding | Buprenorphine: ~96% bound to alpha- and beta-globulins; naloxone: ~45% bound to albumin (primarily). |
| Volume of Distribution | Buprenorphine: Vd ~2.5-4.0 L/kg (large distribution due to lipophilicity); naloxone: Vd ~2.0 L/kg. |
| Bioavailability | Sublingual buprenorphine: ~30-50% (avoid first-pass); sublingual naloxone: ~10% (low); IV: 100% both. |
| Onset of Action | Sublingual: buprenorphine onset 15-30 min, naloxone minimal sublingual absorption; IV: buprenorphine onset 2-5 min, naloxone 1-2 min. |
| Duration of Action | Sublingual: buprenorphine duration 18-24h (long due to high receptor affinity); naloxone: 30-60 min (sublingual negligible effect). |
Sublingual tablet: initially 2/0.5 mg buprenorphine/naloxone, titrated to maintenance 4/1 mg to 24/6 mg once daily; administered sublingually as a single daily dose.
| Dosage form | TABLET |
| Renal impairment | For GFR <30 mL/min: use with caution, dose reduction may be necessary; avoid in severe impairment (creatinine clearance <15 mL/min) due to naloxone accumulation. |
| Liver impairment | Child-Pugh Class A: no adjustment. Child-Pugh Class B: reduce starting dose by 50%, monitor for oversedation. Child-Pugh Class C: not recommended. |
| Pediatric use | Not approved for pediatric patients under 16 years for opioid use disorder; safety and efficacy not established. |
| Geriatric use | Initiate at lower end of dosing range (e.g., 2/0.5 mg sublingually once daily) due to increased sensitivity and potential for hepatic/renal impairment; titrate slowly and monitor for CNS depression. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
No significant drug interactions Can precipitate acute withdrawal in patients dependent on opioids.
| FDA category | Animal |
| Breastfeeding | Limited data; buprenorphine and naloxone are excreted into breast milk in low concentrations. The M/P ratio for buprenorphine is approximately 0.5–2.5, with high interindividual variability. Naloxone has poor oral bioavailability, reducing infant exposure. Benefits of breastfeeding likely outweigh risks if mother is stable on treatment. Monitor infant for sedation, respiratory depression, and adequate weight gain. Avoid use during breastfeeding in cases of high maternal doses or concurrent substance abuse. |
■ FDA Black Box Warning
Risk of respiratory depression, particularly in patients using other CNS depressants, and risk of neonatal opioid withdrawal syndrome with prolonged use during pregnancy.
| Common Effects | Precipitated withdrawal |
| Serious Effects |
["Hypersensitivity to buprenorphine or naloxone","Severe respiratory insufficiency (e.g., acute asthma, COPD)","Severe hepatic impairment","Patients with acute intoxication (alcohol, opioids, benzodiazepines)","Concurrent use of MAO inhibitors (relative contraindication)"]
| Precautions | ["Respiratory depression risk with intravenous administration","Hepatotoxicity (elevated liver enzymes, hepatic failure)","Adrenal insufficiency with chronic use","Interaction with benzodiazepines and other CNS depressants","Precipitation of withdrawal in opioid-dependent patients if administered too soon after last opioid use","Dependence and abuse potential (Schedule III controlled substance)","Neonatal opioid withdrawal syndrome if used during pregnancy"] |
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| Teratogenic Risk |
| Pregnancy category C: First trimester: Limited data; no clear evidence of major malformations, but opioid exposure may be associated with neural tube defects in some studies. Second and third trimesters: Risk of neonatal opioid withdrawal syndrome (NOWS) with chronic use. No known specific teratogenicity; however, maternal opioid use may lead to fetal growth restriction, preterm birth, and stillbirth. Buprenorphine/naloxone is preferred over methadone in pregnancy due to less neonatal respiratory depression and NOWS severity. |
| Fetal Monitoring | Maternal: Baseline liver function tests (LFTs) prior to initiation and periodically; ECG if QT prolongation risk; urine drug screens throughout pregnancy; adherence monitoring. Fetal: Ultrasound for growth restriction, amniotic fluid index, and anatomy; fetal non-stress testing or biophysical profile in third trimester if high risk. Neonatal: Observe for signs of NOWS (e.g., irritability, feeding difficulties, tremors) for at least 72 hours after birth; use validated scoring tools (e.g., Finnegan scale). |
| Fertility Effects | Opioids may cause menstrual irregularities (e.g., amenorrhea, anovulation) due to hypothalamic-pituitary-gonadal axis suppression, which may be reversible upon discontinuation or stabilization. No definitive evidence of permanent infertility. Men may experience decreased libido and erectile dysfunction. Buprenorphine/naloxone may improve fertility outcomes compared to illicit opioid use by stabilizing cycles. Advise women of reproductive age about contraceptive options if not planning pregnancy. |
| Food/Dietary | No significant food interactions; grapefruit juice may increase buprenorphine levels but not considered clinically relevant; alcohol is contraindicated due to additive CNS depression; take on an empty stomach or with food if GI upset occurs. |
| Clinical Pearls | Avoid in patients with known respiratory insufficiency or acute opioid intoxication; use with caution in hepatic impairment; buprenorphine has a ceiling effect for respiratory depression; naloxone component prevents IV abuse; monitor for precipitated withdrawal if initiated too soon after last opioid use; requires at least 12 hours since last short-acting opioid or 24-72 hours for long-acting opioids; can cause QT prolongation at high doses; sublingual absorption is critical; consider dose adjustment in renal impairment. |
| Patient Advice | Place the tablet/film under the tongue until fully dissolved; do not chew, swallow, or crush. · Do not use alcohol or other sedatives (benzodiazepines, muscle relaxants, sleeping pills) as this can cause severe respiratory depression or coma. · Keep out of reach of children and pets; accidental ingestion is life-threatening. · Avoid driving or operating machinery until you know how the medication affects you. · Do not stop suddenly; withdrawal symptoms can occur; taper under medical supervision. · Store at room temperature away from moisture and heat. · Tell all healthcare providers you are taking this medication before any surgery or new prescriptions. · Seek emergency help if you experience difficulty breathing, chest pain, or signs of allergic reaction (rash, swelling). · If you miss a dose, skip it; do not double dose. |