PROBUPHINE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PROBUPHINE (PROBUPHINE).
Partial mu-opioid receptor agonist and weak kappa-opioid receptor antagonist. Also inhibits norepinephrine and dopamine reuptake.
| Metabolism | Primarily metabolized by CYP3A4 and CYP2B6 to norbuprenorphine (active). Glucuronidation via UGT1A1 and UGT2B7. |
| Excretion | Primarily renal (70-80% as unchanged drug and active metabolite norbuprenorphine), biliary/fecal (20-30%) |
| Half-life | Terminal elimination half-life: 37 hours (range 24-48 h) due to slow release from tissue binding and enterohepatic recirculation; contributes to prolonged dosing interval (every 4 weeks) and delayed withdrawal onset. |
| Protein binding | 96% bound to plasma proteins (primarily alpha- and beta-globulins, minor albumin binding) |
| Volume of Distribution | Vd: 2.5-3.0 L/kg; large distribution due to high lipophilicity and extensive tissue binding, indicating slow redistribution. |
| Bioavailability | Sublingual: 30-50% (due to first-pass metabolism). Transdermal: 15-20% (rate-controlled delivery). Oral: <10% (extensive first-pass) and not clinically used. |
| Onset of Action | Sublingual: 30-60 minutes; peak effect at 1-2 hours. Transdermal: 12-24 hours; steady-state achieved by day 3. |
| Duration of Action | Sublingual: 6-8 hours for analgesic effect; maintenance effect on opioid cravings/withdrawal: 24-48 hours. Transdermal: 7 days with wear period; sustained release for 4 weeks with implant. |
| Molecular Weight | 467.6 |
Sublingual: 8 mg to 24 mg once daily initially, then 12-16 mg once daily; maximum 24 mg/day.
| Dosage form | IMPLANT |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment. For severe (CrCl <30 mL/min): not recommended. |
| Liver impairment | Child-Pugh A: no adjustment. Child-Pugh B: reduce dose by 50%. Child-Pugh C: avoid use. |
| Pediatric use | Weight-based: 0.1-0.2 mg/kg sublingually once daily, titrate up to maximum 0.4 mg/kg/day; maximum 24 mg/day. |
| Geriatric use | Start at lower end of dosing range (e.g., 4-8 mg sublingually once daily) with cautious titration due to increased sensitivity and risk of CNS depression. |
| 1st trimester | Limited human data; animal studies show no teratogenicity at therapeutic doses. Use only if benefit outweighs risk. |
| 2nd trimester | Monitor for withdrawal in neonate; may cause preterm labor if abused. Prescribe with caution. |
| 3rd trimester | Neonatal opioid withdrawal syndrome (NOWS) possible; high doses may cause respiratory depression. Assess risk-benefit. |
Clinical note
Comprehensive clinical and safety monograph for PROBUPHINE (PROBUPHINE).
| Placental transfer | Crosses placenta (molecular weight <500 Da, lipophilic); fetal concentrations approximate maternal levels. |
| Breastfeeding | Excreted in breast milk in low levels (RID ~2-3%); monitor infant for sedation and respiratory depression. Generally compatible with breastfeeding under medical supervision. |
■ FDA Black Box Warning
Risk of respiratory depression, especially with concurrent use of CNS depressants or in patients with compromised respiratory function. Risk of neonatal opioid withdrawal syndrome with prolonged use during pregnancy. Potential for life-threatening QT prolongation at high doses.
| Serious Effects |
Hypersensitivity to buprenorphine or any componentSevere respiratory insufficiencyAcute alcoholism or delirium tremensConcurrent use of MAOIs or within 14 daysSevere hepatic impairment (Child-Pugh Class C)
| Precautions | Severe respiratory depression; misuse and abuse potential; neonatal opioid withdrawal syndrome; adrenal insufficiency; hepatotoxicity; QT prolongation; dental decay with sublingual use; opioid withdrawal syndrome with naloxone coadministration. |
| Food/Dietary | No specific food interactions are reported for buprenorphine. However, grapefruit and grapefruit juice may theoretically affect metabolism via CYP3A4 inhibition, altering drug levels. Avoid excessive intake. |
Loading safety data…
| Lactation Rating |
| L3 (Moderately Safe) |
| Teratogenic Risk | Probupine is classified as FDA Pregnancy Category C. In animal studies, it caused fetal harm (increased resorption, skeletal anomalies) at doses 0.5 times the human dose. There are no adequate human studies. First trimester exposure may be associated with neural tube defects; second and third trimester exposure may cause fetal hydantoin syndrome (craniofacial anomalies, growth retardation, neurodevelopmental delay) and increased risk of hemorrhage due to vitamin K depletion. |
| Fetal Monitoring | Monitor maternal serum probupine trough levels (target 10-20 mcg/mL). Assess CBC with differential, liver function tests, coagulation profile (PT/INR) monthly. Fetal surveillance includes ultrasonography for growth and anatomy at 18-20 weeks; nonstress test and biophysical profile in third trimester. Monitor for neonatal withdrawal syndrome after delivery. |
| Fertility Effects | In males, probupine may cause decreased sperm count and motility, and reversible azoospermia. In females, it may cause menstrual irregularities and anovulation. Folate supplementation (5 mg/day) is recommended prior to conception due to antifolate effects. |
| Clinical Pearls | Probupine is not a recognized drug; verify spelling. If referring to buprenorphine, note that it is a partial mu-opioid agonist used for opioid use disorder and pain. Monitor for respiratory depression, especially when combined with CNS depressants. Due to its partial agonist activity, it has a ceiling effect for respiratory depression. High doses may precipitate withdrawal in opioid-dependent patients. Naloxone may not fully reverse buprenorphine effects; consider higher doses or respiratory support. |
| Patient Advice | Take exactly as prescribed; do not change dose or frequency without consulting your doctor. · Avoid alcohol, benzodiazepines, and other sedatives unless directed by your physician, as they increase risk of serious side effects. · Do not stop suddenly; withdrawal may occur. Follow a tapering schedule if discontinuing. · Keep out of reach of children and others; misuse can cause addiction, overdose, or death. · Store safely at room temperature, away from moisture and heat. |