BRIXADI
Clinical safety rating: caution
Comprehensive clinical and safety monograph for BRIXADI (BRIXADI).
Buprenorphine is a partial agonist at mu-opioid receptors and an antagonist at kappa-opioid receptors, reducing opioid withdrawal symptoms and cravings.
| Metabolism | Primarily metabolized by CYP3A4 to norbuprenorphine (active metabolite) via N-dealkylation; also undergoes glucuronidation. |
| Excretion | Primarily fecal (80–90%) as unchanged drug; renal elimination accounts for <5% of the dose. |
| Half-life | Terminal half-life approximately 470–500 hours (~20 days) following intramuscular injection, allowing weekly or monthly dosing. |
| Protein binding | Approximately 99% bound to plasma proteins, primarily albumin and alpha1-acid glycoprotein. |
| Volume of Distribution | Volume of distribution is very large, approximately 500–1000 L (about 5–10 L/kg in a 70 kg individual), indicating extensive tissue binding and sequestration. |
| Bioavailability | Intramuscular injection: bioavailability is nearly 100% due to limited first-pass metabolism; oral bioavailability is <5% due to extensive first-pass metabolism. |
| Onset of Action | Intramuscular injection: onset within 30–60 minutes; intravenous administration produces immediate effect. |
| Duration of Action | Clinically effective mu-opioid receptor blockade persists for at least 28 days after a single intramuscular dose of 300 mg; once weekly dosing maintains continuous blockade. |
| Molecular Weight | 504.4 Da |
Brixadi (buprenorphine) extended-release injection for subcutaneous use: Patients on transmucosal buprenorphine products, after a single dose of 8-24 mg transmucosal buprenorphine, administer Brixadi as a subcutaneous injection once weekly: 8 mg/week for patients on 8-16 mg/day transmucosal buprenorphine, 16 mg/week for patients on 12-24 mg/day, 24 mg/week for patients on 16-24 mg/day. Alternatively, monthly injection: 64 mg/month for patients on 8-16 mg/day, 96 mg/month for patients on 12-24 mg/day, 128 mg/month for patients on 16-24 mg/day.
| Dosage form | SOLUTION, EXTENDED RELEASE |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment. For severe renal impairment (eGFR <30 mL/min/1.73 m2) or end-stage renal disease, use with caution and consider dose reduction due to potential accumulation; specific dosing guidelines not established. |
| Liver impairment | Child-Pugh Class A (mild): No adjustment. Child-Pugh Class B (moderate): Start at lower dose and titrate cautiously; maximum recommended weekly dose 16 mg, monthly dose 96 mg. Child-Pugh Class C (severe): Not recommended due to lack of data. |
| Pediatric use | Not approved for use in pediatric patients; safety and efficacy not established. |
| Geriatric use |
| 1st trimester | Limited human data; animal studies show no teratogenicity at therapeutic doses. Risk of opioid withdrawal in neonate if used chronically. |
| 2nd trimester | Same as T1; may cause fetal dependence and withdrawal after birth with chronic use. |
| 3rd trimester | May cause neonatal opioid withdrawal syndrome (NOWS) after prolonged use. Avoid use near term unless benefits outweigh risks. |
Clinical note
Comprehensive clinical and safety monograph for BRIXADI (BRIXADI).
| Placental transfer | Buprenorphine crosses the placenta; fetal concentrations are approximately 50-70% of maternal serum levels. |
| Breastfeeding | Brixadi (buprenorphine) is excreted into breast milk in low concentrations. Use with caution; monitor infant for drowsiness and feeding difficulties. Consider risk of infant withdrawal if therapy is discontinued. |
■ FDA Black Box Warning
Risk of addiction, abuse, and misuse; life-threatening respiratory depression; neonatal opioid withdrawal syndrome with prolonged use during pregnancy; risk of harm or death from accidental ingestion; concomitant use of benzodiazepines or other CNS depressants may cause profound sedation, respiratory depression, coma, and death.
| Serious Effects |
Hypersensitivity to buprenorphineSevere respiratory insufficiencyAcute alcoholism or delirium tremensConcurrent use of monoamine oxidase inhibitors (MAOIs) or within 14 daysPreexisting moderate to severe hepatic impairment
| Precautions | May cause respiratory depression; risk of abuse potential; need to monitor for hepatic dysfunction; adrenal insufficiency; QT prolongation; precipitation of withdrawal if initiated too soon after full agonist opioids; impairment of mental/physical abilities. |
| Food/Dietary | No specific food interactions are reported for BRIXADI. However, patients should avoid alcohol and grapefruit juice as they may potentiate CNS depression or alter metabolism (grapefruit inhibits CYP3A4, which metabolizes buprenorphine, potentially increasing levels). Advise a balanced diet without restrictions beyond general health recommendations. |
Loading safety data…
| No specific dose adjustments recommended; geriatric patients may have increased sensitivity and should be monitored closely for sedation, respiratory depression, and QTc prolongation. Initiate at lower end of dosing range if severe renal or hepatic impairment present. |
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | Insufficient human data; animal studies show no teratogenicity at clinically relevant doses. Risk cannot be excluded; use only if benefit outweighs risk. |
| Fetal Monitoring | Monitor for neonatal opioid withdrawal syndrome (NOWS) if used near term; assess respiratory status and sedation in mother. |
| Fertility Effects | May impair fertility in females via disruption of gonadal function (hypothalamic-pituitary-gonadal axis suppression); reversible upon discontinuation. |
| Clinical Pearls | BRIXADI (buprenorphine extended-release) is a monthly subcutaneous depot formulation for opioid use disorder (OUD). Initiate only after patient is stabilized on transmucosal buprenorphine (e.g., 8–24 mg/day for at least 7 days). Do not use in opioid-naive patients due to risk of precipitated withdrawal. Administer subcutaneously in the abdomen; avoid intramuscular or intravenous injection. Monitor injection site for nodules, granulomas, or infection. Concomitant use with benzodiazepines or CNS depressants requires careful monitoring due to additive respiratory depression. Liver function tests should be monitored periodically due to risk of hepatic injury. BRIXADI contains buprenorphine as the free base, not salt; dose strengths (64 mg, 96 mg, 128 mg) are not equivalent to other buprenorphine formulations. Upon discontinuation, patients may experience prolonged withdrawal due to slow release over weeks. |
| Patient Advice | BRIXADI is a once-monthly injection to treat opioid dependence and must be given by a healthcare provider only. · Do not attempt to self-administer or remove the injection. The medicine is released slowly over one month. · Notify your doctor immediately if you have trouble breathing, excessive drowsiness, or severe dizziness, especially when combined with alcohol or sedatives. · Avoid use of other opioids (prescription or illicit), as serious side effects including coma or death may occur. · Report any signs of liver problems: dark urine, yellowing skin/eyes, persistent nausea, or abdominal pain. · The injection site may become red, swollen, or painful; contact your doctor if these persist or worsen. · Do not stop BRIXADI suddenly; withdrawal symptoms may occur and can be prolonged. · Keep out of reach of children and pets; accidental exposure can be fatal. |