SUBOXONE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for SUBOXONE (SUBOXONE).
Partial agonist at mu-opioid receptor and antagonist at kappa-opioid receptor; also antagonist at delta-opioid receptor.
| Metabolism | Primarily hepatic via CYP3A4 (N-dealkylation to norbuprenorphine) and to a lesser extent CYP2C8; undergoes glucuronidation. |
| Excretion | Buprenorphine: ~70% fecal, ~30% renal. Norbuprenorphine: ~70% renal, ~30% fecal. |
| Half-life | Buprenorphine: 37 hours (range 20-70) due to slow dissociation from mu-opioid receptors; norbuprenorphine: ~30 hours. |
| Protein binding | Buprenorphine: 96% bound (primarily alpha- and beta-globulins); norbuprenorphine: 97% bound. |
| Volume of Distribution | Buprenorphine: 4.1 L/kg (high tissue distribution, e.g., brain, liver); norbuprenorphine: 3.2 L/kg. |
| Bioavailability | Sublingual: 30-55% (due to first-pass metabolism). Buccal: similar to sublingual. IV: 100%. |
| Onset of Action | Sublingual: 30-60 minutes; peak effect at 1-4 hours. IV: immediate but not clinically used. |
| Duration of Action | Sublingual: 24-36 hours (dose-dependent); allows once-daily dosing for opioid maintenance. |
| Molecular Weight | 504.44 |
Sublingual tablet: Initial dose 2-8 mg buprenorphine/0.5-2 mg naloxone on Day 1; target maintenance 12-16 mg/3-4 mg once daily; maximum 24 mg/6 mg once daily.
| Dosage form | FILM |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment (CrCl ≥30 mL/min). For severe renal impairment (CrCl <30 mL/min), use with caution; reduce dose by 50% and monitor for CNS depression. |
| Liver impairment | Child-Pugh Class A: No adjustment. Class B: Start at lower end of dosing range; titrate slowly. Class C: Avoid use due to risk of precipitated withdrawal or severe toxicity; if necessary, use buprenorphine monotherapy with extreme caution. |
| Pediatric use | Approved for adolescents ≥16 years: Induction dose 2-8 mg/0.5-2 mg sublingually on Day 1; maintenance 12-16 mg/3-4 mg once daily; maximum 24 mg/6 mg per day. Weight-based dosing not established; use adult dosing adjusted for body size. |
| Geriatric use | No specific dose adjustment; start at lower end of dosing range (2 mg/0.5 mg) and titrate slowly due to increased sensitivity and risk of falls or cognitive impairment. |
| 1st trimester | Buprenorphine/naloxone (Suboxone) is associated with a low risk of major malformations; however, neonatal abstinence syndrome (NAS) can occur with third trimester use. Use only if benefit outweighs risk. |
| 2nd trimester | Continued use may be indicated for opioid maintenance therapy; risks of untreated opioid dependence outweigh medication risks. Monitor for dose adjustments. |
| 3rd trimester | Third trimester use may cause neonatal withdrawal. Tapering is not recommended due to relapse risk; treat NAS as needed. |
Clinical note
Comprehensive clinical and safety monograph for SUBOXONE (SUBOXONE).
| Placental transfer | Buprenorphine crosses the placenta; fetal/maternal concentration ratio approximately 0.5–0.6. |
| Breastfeeding | Buprenorphine passes into breast milk in low concentrations. The American Academy of Pediatrics considers buprenorphine compatible with breastfeeding. However, naloxone is poorly absorbed orally and poses minimal risk. Monitor infant for sedation and feeding difficulties. |
■ FDA Black Box Warning
Risk of respiratory depression, particularly during initiation and dose adjustment; potential for abuse and dependence; risk of neonatal opioid withdrawal syndrome with prolonged use during pregnancy; ensure proper patient selection and monitoring.
| Serious Effects |
Hypersensitivity to buprenorphine or naloxoneSevere respiratory insufficiency (e.g., acute asthma)Acute alcoholism or delirium tremensSevere hepatic impairment (Child-Pugh Class C)Concurrent use of MAO inhibitors (or within 14 days)
| Precautions | Respiratory depression (especially with benzodiazepines or alcohol); misuse and diversion potential; QT prolongation; adrenal insufficiency; hepatic impairment; withdrawal precipitation if administered too soon after full agonist opioids; neonatal withdrawal syndrome; risk of overdose in children. |
| Food/Dietary | No specific food interactions; grapefruit juice may theoretically increase buprenorphine levels (CYP3A4), but not clinically significant. Avoid alcohol due to additive CNS depression. |
Loading safety data…
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | Pregnancy category C. First trimester: Limited human data; animal studies show increased risk of neural tube defects at high doses. Second and third trimesters: Risk of neonatal opioid withdrawal syndrome (NOWS) with chronic use. Overall, risk of untreated opioid addiction outweighs potential teratogenic risks. |
| Fetal Monitoring | Monitor for signs of respiratory depression or sedation in the newborn. Assess for NOWS using standardized scoring (e.g., Finnegan). Maternal monitoring: liver function tests, adherence to treatment, and concurrent substance use. Fetal ultrasound for growth if indicated. |
| Fertility Effects | Limited data. Buprenorphine may cause menstrual irregularities and anovulation due to opioid-induced hypothalamic-pituitary-gonadal axis suppression. Effects are dose-dependent; recovery of fertility may occur with dose reduction or discontinuation. No evidence of permanent infertility. |
| Clinical Pearls | SUBOXONE contains buprenorphine and naloxone; buprenorphine is a partial mu-opioid agonist with ceiling effect reducing respiratory depression risk, but can precipitate withdrawal if given too soon after full agonists (wait at least 12-24h after short-acting opioids, 24-72h for methadone). Naloxone is poorly absorbed sublingually but injected to deter misuse. Monitor liver function tests due to hepatotoxicity risk. Avoid use with benzodiazepines or CNS depressants; may require dose adjustment. Induction should be done in medically supervised setting. Use in pregnancy may cause neonatal abstinence syndrome. |
| Patient Advice | Place tablet under tongue until fully dissolved (about 5-10 minutes); do not chew or swallow. · Do not take other opioids, alcohol, or sedatives while on this medication. · Common side effects: headache, nausea, constipation, or trouble sleeping; report severe drowsiness or breathing problems. · Do not stop suddenly; taper under medical supervision to avoid withdrawal. · Keep out of reach of children; accidental ingestion is dangerous. · Inform all healthcare providers you are taking this medication. |