The recommended weekly dose in patients not currently receiving buprenorphine treatment is 24 mg of BRIXADI (weekly) titrated up over the first week of treatment as follows:
- To avoid precipitating an opioid withdrawal syndrome, administer a test dose of transmucosal buprenorphine 4 mg when objective signs of mild to moderate withdrawal appear.
- If the dose of transmucosal buprenorphine is tolerated without precipitated withdrawal, administer the first dose of BRIXADI (weekly), 16 mg.
- Administer an additional dose of 8 mg BRIXADI (weekly) within 3 days of the first dose to achieve the recommended 24 mg BRIXADI (weekly) dose.
If needed, during this first week of treatment, administer an additional 8 mg dose of BRIXADI (weekly), waiting at least 24 hours after the previous injection, for a total weekly dose of 32 mg BRIXADI (weekly).
Administer subsequent BRIXADI (weekly) injections based on the total weekly dose that was established during Week One. Dosage adjustments can be made at weekly appointments with the maximum BRIXADI (weekly) dose being 32 mg.
A patient who misses a dose of BRIXADI (weekly) should receive the next dose as soon as possible. BRIXADI (weekly) should be administered in 7-day intervals.
Patients Switching from Transmucosal Buprenorphine-containing Products to BRIXADI
Patients currently being treated with a transmucosal buprenorphine-containing product may be switched directly to either BRIXADI (weekly) or BRIXADI (monthly).
Table 1 identifies the corresponding dose of BRIXADI when switching a patient from transmucosal buprenorphine to BRIXADI (weekly) or BRIXADI (monthly), expressing the transmucosal dose equivalents in terms of Subutex or Suboxone doses.
Table 1: Daily doses of sublingual buprenorphine (Subutex, Suboxone, or generic product equivalents) and suggested corresponding BRIXADI (weekly) or BRIXADI (monthly) doses| Daily dose of sublingual buprenorphine | BRIXADI (weekly) | BRIXADI (monthly) |
|---|
| Note: One SUBOXONE® (buprenorphine and naloxone) 8 mg/2 mg sublingual tablet provides equivalent buprenorphine exposure to one SUBUTEX® (buprenorphine HCl) 8 mg sublingual tablet or one Zubsolv® (buprenorphine and naloxone) 5.7 mg/1.4 mg sublingual tablet. |
| ≤ 6 mg | 8 mg | -- |
| 8-10 mg | 16 mg | 64 mg |
| 12-16 mg | 24 mg | 96 mg |
| 18-24 mg | 32 mg | 128 mg |
Patients Transitioning Between BRIXADI (weekly) and BRIXADI (monthly)
Patients may be transitioned from weekly to monthly or from monthly to weekly dosing of BRIXADI based on clinical judgment (see Table 2).
Table 2: Recommended dose when transitioning between BRIXADI (weekly) and BRIXADI (monthly)| BRIXADI (weekly) | BRIXADI (monthly) |
|---|
| 16 mg | 64 mg |
| 24 mg | 96 mg |
| 32 mg | 128 mg |
A patient who misses a dose of BRIXADI should receive the next dose as soon as possible. BRIXADI (weekly) should be administered in 7-day intervals. BRIXADI (monthly) should be administered in 28-day intervals.
Dose Adjustments of BRIXADI
An additional BRIXADI (weekly) 8 mg injection may be administered, based on clinical judgment during a dosing interval, up to a maximum dose of 32 mg per week of BRIXADI (weekly) or 128 mg per month of BRIXADI (monthly).
Patient Access to Naloxone for the Emergency Treatment of Opioid Overdose
Discuss the availability of naloxone for the emergency treatment of opioid overdose with the patient and caregiver.
Because patients being treated for opioid use disorder have the potential for relapse, putting them at risk for opioid overdose, strongly consider prescribing naloxone for the emergency treatment of opioid overdose, both when initiating and renewing treatment with BRIXADI. Also consider prescribing naloxone if the patient has household members (including children) or other close contacts at risk for accidental ingestion or opioid overdose [see Dosage and Administration (2.2)].
Advise patients and caregivers that naloxone may also be administered for a known or suspected overdose with buprenorphine itself. Higher than normal doses and repeated administration of naloxone may be necessary due to the long duration of action of buprenorphine and its affinity for the mu receptor [see Overdosage (10)].
Inform patients and caregivers of their options for obtaining naloxone as permitted by individual state naloxone dispensing and prescribing requirements or guidelines (e.g., by prescription, directly from a pharmacist, or as part of a community-based program).
Educate patients and caregivers on how to recognize respiratory depression and, if naloxone is prescribed, how to treat with naloxone. Emphasize the importance of calling 911 or getting emergency medical help, even if naloxone is administered [see Patient Counseling Information (17)].
Latex Allergies: The BRIXADI needle cap is synthetically derived from natural rubber latex which may cause allergic reactions in latex-sensitive individuals.
Risk Summary
The data on use of buprenorphine, the active ingredient in BRIXADI in pregnancy, are limited; however, these data do not indicate an increased risk of major malformations specifically due to buprenorphine exposure. There are limited data from randomized clinical trials in women maintained on sublingual buprenorphine that were not designed appropriately to assess the risk of major malformations [see Data].
Embryofetal death was observed in both rats and rabbits administered buprenorphine during the period of organogenesis at doses 21 times and equal to, respectively, the mean daily dose of 4.6 mg buprenorphine delivered by either 32 mg BRIXADI (weekly) or 128 mg BRIXADI (monthly). Pre- and post-natal development studies in rats demonstrated increased neonatal deaths at doses approximately equal to and above and dystocia at 11 times the mean daily dose of 4.6 mg buprenorphine. No clear teratogenic effects were seen when buprenorphine was administered during organogenesis with a range of doses 4 times and greater than the mean daily dose of 4.6 mg of buprenorphine. However, increases in skeletal abnormalities were noted in rats and rabbits administered buprenorphine daily during organogenesis at doses 2 and 21 times the mean daily dose of 4.6 mg of buprenorphine, respectively. In a few studies, some events such as acephalus and omphalocele were also observed but these findings were not clearly treatment-related [see Data]. Based on animal data, advise pregnant women of the potential risk to a fetus.
The estimated background risk of major birth defects and miscarriage for the indicated population are unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively.
BRIXADI should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus
Clinical Considerations
Disease-associated maternal and embryo-fetal risk
Untreated opioid addiction in pregnancy is associated with adverse obstetrical outcomes such as low birth weight, preterm birth, and fetal death. In addition, untreated opioid addiction often results in continued or relapsing illicit opioid use.
Dose Adjustment during Pregnancy and the Postpartum Period
Dosage adjustments of buprenorphine may be required during pregnancy, even if the patient was maintained on a stable dose prior to pregnancy. Withdrawal signs and symptoms should be monitored closely, and the dose adjusted as necessary.
Fetal/neonatal adverse reactions
Neonatal opioid withdrawal syndrome may occur in newborn infants of mothers who are receiving treatment with BRIXADI.
Neonatal opioid withdrawal syndrome presents as irritability, hyperactivity, and abnormal sleep pattern, high pitched cry, tremor, vomiting, diarrhea, and/or failure to gain weight. Signs of neonatal withdrawal usually occur in the first days after birth. The duration and severity of neonatal opioid withdrawal syndrome may vary. Observe newborns for signs of neonatal opioid withdrawal syndrome and manage accordingly [see Warnings and Precautions (5.6)].
Labor or Delivery
Opioid-dependent women on buprenorphine maintenance therapy may require additional analgesia during labor.
As with all opioids, use of buprenorphine prior to delivery may result in respiratory depression in the newborn. Closely monitor neonates for signs of respiratory depression. An opioid antagonist such as naloxone should be available for reversal of opioid induced respiratory depression in the neonate.
Data
Human Data
Studies have been conducted to evaluate neonatal outcomes in women exposed to buprenorphine during pregnancy. Limited data from trials, observational studies, case series, and case reports on buprenorphine use in pregnancy do not indicate an increased risk of major malformations specifically due to buprenorphine. Several factors may complicate the interpretation of investigations of the children of women who take buprenorphine during pregnancy, including maternal use of illicit drugs, late presentation for prenatal care, infection, poor compliance, poor nutrition, and psychosocial circumstances. Interpretation of data is complicated further by the lack of information on untreated opioid-dependent pregnant women, who would be the most appropriate group for comparison. Rather, women on another form of opioid medication-assisted treatment, or women in the general population are generally used as the comparison group. However, women in these comparison groups may be different from women prescribed buprenorphine-containing products with respect to maternal factors that may lead to poor pregnancy outcomes.
In a multicenter, double-blind, randomized, controlled trial (Maternal Opioid Treatment: Human Experimental Research [MOTHER]) designed primarily to assess neonatal opioid withdrawal effects, opioid-dependent pregnant women were randomized to buprenorphine (n=86) or methadone (n=89) treatment, with enrollment at an average gestational age of 18.7 weeks in both groups. A total of 28 of the 86 women in the buprenorphine group (33%) and 16 of the 89 women in the methadone group (18%) discontinued treatment before the end of pregnancy.
Among women who remained in treatment until delivery, there was no difference between buprenorphine-treated and methadone-treated groups in the number of neonates requiring NOWS treatment or in the peak severity of NOWS. Buprenorphine-exposed neonates required less morphine (mean total dose, 1.1 mg vs 10.4 mg), had shorter hospital stays (10.0 days vs 17.5 days), and shorter duration of treatment for NOWS (4.1 days vs 9.9 days) compared to the methadone-exposed group. There were no differences between groups in other primary outcomes (neonatal head circumference) or secondary outcomes (weight and length at birth, preterm birth, gestational age at delivery, and 1-minute and 5-minute Apgar scores), or in the rates of maternal or neonatal adverse events. The outcomes among mothers who discontinued treatment before delivery and may have relapsed to illicit opioid use are not known. Because of the imbalance in discontinuation rates between the buprenorphine and methadone groups, the study findings are difficult to interpret.
Animal Data
The exposure margins below are based on the mean daily dose of 4.6 mg buprenorphine delivered by 32 mg BRIXADI (weekly) or 128 mg BRIXADI (monthly) on body surface area comparisons, unless otherwise noted.
No definitive drug-related teratogenic effects were observed in rats and rabbits at IM doses up to 30 mg/kg/day (64 times and 127 times, respectively, on a mg/m2 basis). Maternal toxicity resulting in mortality was noted in these studies in both rats and rabbits. Acephalus was observed in one rabbit fetus from the low-dose group and omphalocele was observed in two rabbit fetuses from the same litter in the mid-dose group; no findings were observed in fetuses from the high-dose group. Maternal toxicity was seen in the high-dose group but not at the lower doses where the findings were observed. Following oral administration of buprenorphine to rats, dose-related post-implantation losses, evidenced by increases in the numbers of early resorptions with consequent reductions in the numbers of fetuses, were observed at doses of 10 mg/kg/day or greater (21 times on a mg/m2 basis). In the rabbit, increased post-implantation losses occurred at an oral dose of 40 mg/kg/day (169 times on a mg/m2 basis). Following IM administration in the rat and the rabbit, post-implantation losses, as evidenced by decreases in live fetuses and increases in resorptions, occurred at 30 mg/kg/day (64 times and 127 times, respectively, on a mg/m2 basis).
Buprenorphine was not teratogenic in rats and rabbits after subcutaneous (SC) doses of up to 5 mg/kg/day (9 and 5 times in rat, and 12 and 7 times in rabbit the highest daily exposure from 32 mg BRIXADI (weekly) or 128 mg BRIXADI (monthly), respectively, on an AUC basis), after intramuscular (IM) doses of up to 5 mg/kg/day (11 and 21 times on a mg/m2 basis), after IV doses up to 0.8 mg/kg/day (2 and 3 times on a mg/m2 basis), or after oral doses up to 160 mg/kg/day in rats (338 times on a mg/m2 basis) and 25 mg/kg/day in rabbits (106 times on a mg/m2 basis). Significant increases in skeletal abnormalities (e.g., extra thoracic vertebra or thoraco-lumbar ribs) were noted in rats after SC administration of 1 mg/kg/day and up (2.4 or 1.5 times the highest daily exposure from 32 mg BRIXADI (weekly) or 128 mg BRIXADI (monthly), respectively, on an AUC basis, but were not observed at oral doses up to 160 mg/kg/day (338 times on a mg/m2 basis).
Increases in skeletal abnormalities in rabbits after IM administration of 5 mg/kg/day (21 times on a mg/m2 basis) in the absence of maternal toxicity or oral administration of 1 mg/kg/day or greater (4 times on a mg/m2 basis) were not statistically significant. In rabbits, buprenorphine produced statistically significant pre-implantation losses at oral doses of 1 mg/kg/day or greater (4 times on a mg/m2 basis) and post-implantation losses that were statistically significant at IV doses of 0.2 mg/kg/day or greater (approximately equal on a mg/m2 basis). No maternal toxicity was noted at doses causing post-implantation loss in this study.
Dystocia was noted in pregnant rats treated intramuscularly with buprenorphine from Gestation Day 14 through Lactation Day 21 at 5 mg/kg/day (11 times on a mg/m2 basis). Fertility and pre- and post-natal development studies with buprenorphine in rats indicated increases in neonatal mortality after oral doses of 0.8 mg/kg/day and up (2 times on a mg/m2 basis), after IM doses of 0.5 mg/kg/day and up (approximately equal on a mg/m2 basis), and after SC doses of 0.1 mg/kg/day and up (0.4 or 0.3 times the highest daily exposure from 32 mg BRIXADI (weekly) or 128 mg BRIXADI (monthly), respectively, on an AUC basis). An apparent lack of milk production during these studies likely contributed to the decreased pup viability and lactation indices. Delays in the occurrence of righting reflex and startle response were noted in rat pups at an oral dose of 80 mg/kg/day (169 times on a mg/m2 basis).
Risk Summary
Based on two studies in 13 lactating women maintained on sublingual buprenorphine treatment, buprenorphine and its metabolite norbuprenorphine were present in low levels in human milk. Available data have not shown adverse reactions in breastfed infants. The development and health benefits of breastfeeding should be considered along with the mother's clinical need for buprenorphine treatment and any potential adverse effects on the breastfed child from the drug or from the underlying maternal condition.
Clinical Considerations
Advise the nursing mother taking buprenorphine to monitor the infant for increased drowsiness and breathing difficulties.
Data
Data were consistent from two studies (N=13) of breastfeeding infants whose mothers were maintained on sublingual doses of buprenorphine ranging from 2.4 to 24 mg/day, showing that the infants were exposed to less than 1% of the maternal daily dose.
In a study of six lactating women who were taking a median sublingual buprenorphine dose of 0.29 mg/kg/day 5 to 8 days after delivery, breast milk provided a median infant dose of 0.42 mcg/kg/day of buprenorphine and 0.33 mcg/kg/day of norbuprenorphine, equal to 0.2% and 0.12% respectively, of the maternal weight-adjusted dose (relative dose/kg [%] of norbuprenorphine was calculated from the assumption that buprenorphine and norbuprenorphine are equipotent).
Data from a study of seven lactating women who were taking a median (sublingual buprenorphine) dose of 7 mg/day an average of 1.12 months after delivery indicated that the mean milk concentrations (Cavg) of buprenorphine and norbuprenorphine were 3.65 mcg/L and 1.94 mcg/L respectively. Based on the study data, and assuming milk consumption of 150 mL/kg/day, an exclusively breastfed infant would receive an estimated mean absolute infant dose (AID) of 0.55 mcg/kg/day of buprenorphine and 0.29 mcg/kg/day of norbuprenorphine, or a mean relative infant dose (RID) of 0.38% and 0.18%, respectively, of the maternal weight-adjusted dose.
Infertility
Chronic use of opioids may cause reduced fertility in females and males of reproductive potential. It is not known whether these effects on fertility are reversible [see Adverse Reactions (6.2), Clinical Pharmacology (12.2), Nonclinical Toxicology (13.1)].
Clinical Presentation
The manifestations of acute buprenorphine overdose include pinpoint pupils, sedation, hypotension, respiratory depression, and death.
Treatment of Overdose
In the event of overdose, the respiratory and cardiac status of the patient should be monitored carefully. When respiratory or cardiac functions are depressed, primary attention should be given to the re‐establishment of adequate respiratory exchange through provision of a patent airway and institution of assisted or controlled ventilation. Oxygen, IV fluids, vasopressors, and other supportive measures should be considered as indicated. Naloxone may be of value for the management of buprenorphine overdose. Higher than normal doses and repeated administration may be necessary.
Clinicians should consider the potential role and contribution of buprenorphine, other opioids, and other CNS depressant drugs in a patient's clinical presentation.
Opioid Blockade
The opioid blockade study assessed the blockade of subjective opioid drug-liking effects and pharmacokinetics (PK) of BRIXADI (weekly) in 47 patients with moderate or severe opioid dependence. The primary endpoint was the maximum rating (Emax) on the visual analogue scale (VAS) for drug-liking. After stabilization on immediate-release morphine, all patients completed a 3-day qualification/baseline hydromorphone challenge session consisting of 3 intramuscular doses of hydromorphone (0 mg, [placebo], 6 mg, and 18 mg) once daily for 3 consecutive days in a randomized, double-blind, crossover manner. Following the qualification phase, eligible patients received 2 injections of BRIXADI (weekly) for two weeks at either the 24 mg or 32 mg level. Two hydromorphone challenge sessions (3 consecutive days each) were conducted throughout the week after each weekly injection of BRIXADI (weekly).
On average, the subjective effects (e.g., drug liking [Emax]) of 6 mg or 18 mg hydromorphone was blocked following injections of BRIXADI (weekly) at the 24 mg or 32 mg levels. The variability in drug-liking scores was wider for the 18 mg than the 6 mg hydromorphone dose level. In addition, for the 18 mg hydromorphone dose challenge, the drug-liking score variability was wider towards the end of the BRIXADI (weekly) dosing interval compared to earlier in the interval (e.g. Days 4-6 versus Days 1-3; Day 11-13 versus Day 8-10). Drug-liking score variability was wider for the 24 mg BRIXADI (weekly) dose level compared to 32 mg [see Clinical Studies (14.1)].
Figure 14 illustrates the relationship between buprenorphine plasma level and drug liking after 18 mg hydromorphone where data from the 24 mg BRIXADI (weekly) arm is pooled with data from the 32 mg BRIXADI (weekly) arm. The observed plateau for maximal response of drug-liking was reached at buprenorphine concentrations of approximately 1.5-2 ng/mL plasma levels.
Figure 14: Placebo-Corrected Drug Liking VAS vs. Plasma Buprenorphine Concentration Following 18 mg Hydromorphone Challenges for Pooled 24 mg and 32 mg Arms
Androgen Deficiency
Chronic use of opioids may influence the hypothalamic-pituitary-gonadal axis, leading to androgen deficiency that may manifest as low libido, impotence, erectile dysfunction, amenorrhea, or infertility.
The causal role of opioids in the clinical syndrome of hypogonadism is unknown because the various medical, physical, lifestyle, and psychological stressors that may influence gonadal hormone levels have not been adequately controlled for in studies conducted to date. Patients presenting with symptoms of androgen deficiency should undergo laboratory evaluation.
Cardiac Electrophysiology
Thorough QT studies with buprenorphine products have demonstrated modest QT prolongation ≤15 msec. Two categorical analyses of cardiovascular-specific adverse events among patients exposed to buprenorphine demonstrated no proarrhythmic potential. One Holter monitoring study demonstrated no arrhythmia. An analysis of medical literature provided no evidence for causal association between buprenorphine and Torsades de Pointes.
Physiological Effects
Buprenorphine in IV (2, 4, 8, 12 and 16 mg) and sublingual (12 mg) doses have been administered to opioid-experienced subjects who were not physically dependent to examine cardiovascular, respiratory, and subjective effects at doses comparable to those used for treatment of opioid use disorder. Compared to placebo, there were no statistically significant differences among any of the treatment conditions for blood pressure, heart rate, respiratory rate, O2 saturation, or skin temperature across time. Systolic BP was higher in the 8 mg group than placebo (3-hour AUC values). Minimum and maximum effects were similar across all treatments. Subjects remained responsive to low voice and responded to computer prompts. Some subjects showed irritability, but no other changes were observed.
The respiratory effects of sublingual buprenorphine were compared with the effects of methadone in a double-blind, parallel group, dose ranging comparison of single doses of buprenorphine sublingual solution (1, 2, 4, 8, 16, or 32 mg) and oral methadone (15, 30, 45, or 60 mg) in non-dependent, opioid-experienced volunteers. In this study, hypoventilation not requiring medical intervention was reported more frequently after buprenorphine doses of 4 mg and higher than after methadone. Both drugs decreased O2 saturation to the same degree.
In clinical studies conducted with BRIXADI at doses ranging from 7.5 to 32 mg for weekly BRIXADI and 64 to 192 mg for monthly BRIXADI, no incidences of temperature elevations, or clinically significant lowering of oxygen saturation were observed.
Absorption
BRIXADI is an extended-release formulation of buprenorphine designed for subcutaneous administration. BRIXADI is available in two regimens: weekly and monthly. Following single doses of BRIXADI (weekly) or BRIXADI (monthly), the buprenorphine Cmax and AUCinf increase dose-proportionally.
The steady-state PK of buprenorphine following BRIXADI (weekly), BRIXADI (monthly) and their comparison to sublingual SUBUTEX across three studies are shown in Table 7. In these studies, BRIXADI (weekly) was administered for 4 or 4 to 7 weekly doses, BRIXADI (monthly) was administered for 4 monthly doses, and SUBUTEX was administered for 7 daily doses.
After BRIXADI subcutaneous injection, the buprenorphine plasma concentration increases with a median time to maximum plasma concentration (tmax) of about 24 hours for BRIXADI (weekly) and 6-10 hours for BRIXADI (monthly). Based on trough levels after each dose, steady-state exposure is reached at administration of the fourth weekly or monthly dose.
After four repeated doses of BRIXADI (weekly) (16 mg) AUCτ (0-7d), Cmax and Ctrough values are ~40% higher exposure compared to the first dose. Based on cross-study comparisons, four repeated doses of BRIXADI (monthly) (128 mg) results in 68%, 65%, and 124% higher AUCτ (0-28d), Cmax and Ctrough values, respectively compared to the first dose.
Table 7: Summary of steady-state PK parameters of buprenorphine after subcutaneous buttock injections of BRIXADI (weekly) and BRIXADI (monthly) and sublingual (SL) administration of SUBUTEX| Drug product dose | Cav (ng/mL) | Cmax (ng/mL) | Ctrough C168h after 4th dose for BRIXADI (weekly), C28d after 4th dose for BRIXADI (monthly) and C24h after 7th daily dose for Subutex (ng/mL) |
|---|
| SL BPN | Brixadi (weekly) | Brixadi (monthly) | SL BPN Average value of two studies | Brixadi (weekly) | Brixadi (monthly) | SL BPN | Brixadi (weekly) | Brixadi (monthly) | SL BPN | Brixadi (weekly) | Brixadi (monthly) |
|---|
| 8 mg | 16 mg | 64 mg | 1.2 | 2.1 | 2.0 Simulated | 4.7 | 4.3 | 4.0 | 0.7 | 0.8 | 1.3 |
| 16 mg | 24 mg | 96 mg | 1.8 | 2.9 | 2.9 | 6.5 | 5.5 | 6.0 | 1.0 | 1.4 | 2.0 |
| 24 mg | 32 mg | 128 mg | 2.5 | 4.2 | 3.9 | 8.2 | 6.9 | 11.1 | 1.4 | 2.6 | 2.1 |
Effect of injection Site on PK of BRIXADI
After multiple dose subcutaneous injections of 32 mg BRIXADI weekly product at different injection sites (abdomen, thigh, buttock or upper arm), a comparable PK exposure was observed. However, injection in the arm site was associated with approximately 10% lower plasma levels than other sites.
Distribution:
Buprenorphine is approximately 96% protein bound, primarily to alpha and beta globulin.
Elimination:
Buprenorphine is metabolized and eliminated in urine and feces. The apparent terminal plasma half-life of buprenorphine following subcutaneous injection of BRIXADI ranged between 3 to 5 days for BRIXADI (weekly) and 19 to 26 days for BRIXADI (monthly) as a result of the slow release of buprenorphine from the subcutaneous depot.
Metabolism:
Buprenorphine undergoes both N-dealkylation to norbuprenorphine and glucuronidation. The N-dealkylation pathway is mediated primarily by the CYP3A4. Norbuprenorphine, the major metabolite, can further undergo glucuronidation. Norbuprenorphine has been found to bind opioid receptors in vitro; however, it has not been studied clinically for opioid-like activity.
Norbuprenorphine steady-state plasma concentrations in humans after subcutaneous injection of BRIXADI (weekly or monthly) are low compared to buprenorphine (AUC norbuprenorphine/ buprenorphine ratio of 0.35).
Excretion:
A mass balance study of buprenorphine showed complete recovery of radiolabel in urine (30%) and feces (69%) collected up to 11 days after dosing. Almost all of the dose was accounted for in terms of buprenorphine, norbuprenorphine, and two unidentified buprenorphine metabolites. In urine, most of the buprenorphine and norbuprenorphine was conjugated (buprenorphine, 1% free and 9.4% conjugated; norbuprenorphine, 2.7% free and 11% conjugated). In feces, almost all of the buprenorphine and norbuprenorphine were free (buprenorphine, 33% free and 5% conjugated; norbuprenorphine, 21% free and 2% conjugated).
Drug Interaction Studies:
CYP3A4 Inhibitors and Inducers
The effects of co-administered CYP3A4 inhibitors and inducers on buprenorphine exposure in subjects treated with BRIXADI have not been studied; however, such interactions have been established in studies using transmucosal buprenorphine. The effects of buprenorphine may be dependent on the route of administration.
Buprenorphine is metabolized to norbuprenorphine primarily by cytochrome CYP3A4; therefore, potential interactions may occur when BRIXADI is given concurrently with agents that affect CYP3A4 activity. The effects of co-administered CYP3A4 inducers or inhibitors have been established in studies using transmucosal buprenorphine. Patients who switch to BRIXADI treatment from a regimen for transmucosal buprenorphine used concomitantly with CYP3A4 inhibitors (e.g., ketoconazole, macrolide antibiotics (e.g., erythromycin) or HIV protease inhibitors, or CYP3A4 inducer (e.g., phenobarbital, carbamazepine, phenytoin, rifampicin) should be monitored to ensure that the plasma buprenorphine level provided by BRIXADI is adequate and not excessive [see Drug Interactions (7)].
Buprenorphine has been found to be a CYP2D6 and CYP3A4 inhibitor and its major metabolite, norbuprenorphine, has been found to be a moderate CYP2D6 inhibitor in in vitro studies employing human liver microsomes. However, plasma concentrations of buprenorphine and norbuprenorphine resulting from therapeutic BRIXADI doses are not expected to significantly affect the metabolism (systemic exposure) of other concomitantly administered medications [see Drug Interactions (7)].
Specific Populations
Based on population pharmacokinetic analyses, age, sex and race do not have a clinically meaningful effect on PK of BRIXADI.
Hepatic Impairment
The effect of hepatic impairment on the pharmacokinetics of BRIXADI has not been studied.
In a pharmacokinetic study, the disposition of buprenorphine was determined after administering a 2.0/0.5 mg Suboxone (buprenorphine/naloxone) sublingual tablet in subjects with varied degrees of hepatic impairment as indicated by Child-Pugh criteria. The disposition of buprenorphine in patients with hepatic impairment was compared to disposition in subjects with normal hepatic function.
In subjects with mild hepatic impairment, the changes in mean Cmax, AUC0-last, and half-life values of buprenorphine were not clinically significant.
For subjects with moderate and severe hepatic impairment, mean Cmax, AUC0-last, and half-life values of buprenorphine were increased [see Warnings and Precautions (5.14) and Use in Specific Populations (8.6)].
Renal Impairment
The effect of renal impairment on the pharmacokinetics of BRIXADI has not been studied. Clinical studies of BRIXADI did not include subjects with severe renal impairment. Less than 1% is excreted as unchanged buprenorphine in urine following IV buprenorphine administration. No differences in buprenorphine pharmacokinetics were observed between 9 dialysis-dependent and 6 normal patients following IV administration of 0.3 mg buprenorphine [see Use in Specific Populations (8.7)].
Population PK analyses indicated no notable relationship between creatinine clearance and steady-state buprenorphine plasma concentrations.
HCV infection
In subjects with HCV infection but no sign of hepatic impairment, the changes in the mean Cmax, AUC0-last, and half-life values of buprenorphine were not clinically significant in comparison to healthy subjects without HCV infection.
Carcinogenicity
Carcinogenicity studies of buprenorphine were conducted in Sprague-Dawley rats and CD-1 mice. Buprenorphine was administered in the diet to rats for 27 months at doses of 0.6, 5.5, and 56 mg/kg/day (0.3, 1.4 and 11.3 times the highest daily exposure from 32 mg BRIXADI (weekly) on an AUC basis and 0.2, 0.9 and 6.9 times the highest daily exposure from 128 mg BRIXADI (monthly) on an AUC basis). A statistically significant dose-related increase in Leydig cell tumors occurred. In an 86-week study in CD-1 mice, buprenorphine was not carcinogenic at dietary doses up to 100 mg/kg/day (7 and 4 times the highest daily exposure from 32 mg BRIXADI (weekly) or 128 mg BRIXADI (monthly), respectively, on an AUC basis).
NMP, an excipient in BRIXADI (monthly) produced an increase in hepatocellular adenomas and carcinomas in male and female mice at 47 and 60 times, respectively, the maximum daily dose (MDD) of NMP via 128 mg BRIXADI (monthly) on a mg/m2 basis. The clinical significance of these findings is unclear. No tumors were noted in male or female mice at 7.4 and 9.5 times the MDD on a mg/m2 basis. In 2-year inhalation and dietary studies in rats, NMP did not result in evidence of carcinogenicity.
Mutagenicity
Buprenorphine was studied in a series of tests utilizing gene, chromosome, and DNA interactions in both prokaryotic and eukaryotic systems. Results were negative in yeast (S. cerevisiae) for recombinant, gene convertant, or forward mutations; negative in Bacillus subtilis "rec" assay; negative for clastogenicity in CHO cells, Chinese hamster bone marrow and spermatogonia cells, and negative in the mouse lymphoma L5178Y assay.
Results were equivocal in the Ames test: negative in studies in two laboratories, but positive for frame shift mutation at a high dose (5 mg/plate) in a third study. Results were positive in the Green-Tweets (E. coli) survival test, positive in a DNA synthesis inhibition (DSI) test with testicular tissue from mice, for both in vivo and in vitro incorporation of [3 H]thymidine, and positive in unscheduled DNA synthesis test using testicular cells from mice.
Impairment of Fertility
Reproduction studies of buprenorphine in rats demonstrated no evidence of impaired fertility at daily oral doses up to 80 mg/kg/day (169 times the mean daily dose of 4.6 mg buprenorphine as delivered by 32 mg BRIXADI (weekly) or 128 mg BRIXADI (monthly) on a mg/m2 basis) or up to 5 mg/kg/day IM (11 times the mean daily dose of 4.6 mg buprenorphine as delivered by 32 mg BRIXADI (weekly) or 128 mg BRIXADI (monthly) on a mg/m2 basis) or 5 mg/kg/day SC (16 or 10 times the highest daily exposure from 32 mg BRIXADI (weekly) or 128 mg BRIXADI (monthly), respectively, on an AUC basis).
Safe Use
Before initiating treatment with BRIXADI, explain the points listed below to patients and caregivers.
BRIXADI Risk Evaluation and Mitigation Strategy (REMS)
Advise patients that because of the risk of serious harm or death due to intravenous self-administration, BRIXADI is available only through a restricted distribution program called the BRIXADI REMS. Healthcare settings and pharmacies are certified and only dispense BRIXADI directly to a healthcare provider for administration by a healthcare provider [see Warnings and Precautions (5.2)].
Life Threatening Respiratory Depression
Educate patients and caregivers on how to recognize respiratory depression and emphasize the importance of calling 911 or getting emergency medical help right away in the event of a known or suspected overdose [see Warnings and Precautions 5.4)].
Patient Access to Naloxone for the Emergency Treatment of Opioid Overdose
Because patients being treated for opioid use disorder are at risk for relapse, discuss the importance of having access to naloxone with the patient and caregiver. Also discuss the importance of having access to naloxone if there are household members (including children) or other close contacts at risk for accidental ingestion or opioid overdose.
Inform patients and caregivers of the options for obtaining naloxone as permitted by individual state naloxone dispensing and prescribing requirements or guidelines (e.g., by prescription, directly from a pharmacist, or as part of a community-based program).
Educate patients and caregivers on how to recognize the signs and symptoms of an opioid overdose.
Explain to patients and caregivers that naloxone's effects are temporary, and that they must call 911 or get emergency medical help right away in all cases of known or suspected opioid overdose, even if naloxone is administered. Repeat administration may be necessary, particularly for overdose involving buprenorphine, because naloxone is often not effective at the doses available for patient access [Dosage and Administration (2.3), Warnings and Precautions (5.4), Overdosage (10)].
If naloxone is prescribed, also advise patients and caregivers:
- How to treat with naloxone in the event of an opioid overdose
- To tell family and friends about their naloxone and to keep it in a place where family and friends can easily access it in an emergency
- To read the Patient Information (or other educational material) that will come with their naloxone. Emphasize the importance of doing this before an opioid emergency happens, so the patient and caregiver will know what to do.
Interaction with Benzodiazepines and other CNS Depressants
Inform patients and caregivers that potentially fatal additive effects may occur if BRIXADI is used with benzodiazepines or other CNS depressants, including alcohol, and not to use these concomitantly unless supervised by a healthcare provider [see Warnings and Precautions (5.5) and Drug Interactions (7)].
Serotonin Syndrome
Inform patients that BRIXADI could cause a rare but potentially life-threatening condition resulting from concomitant administration of serotonergic drugs. Warn patients of the symptoms of serotonin syndrome and to seek medical attention right away if symptoms develop. Instruct patients to inform their physicians if they are taking, or plan to take serotonergic medications [see Drug Interactions (7)].
Adrenal Insufficiency
Inform patients that BRIXADI could cause adrenal insufficiency, a potentially life-threatening condition. Adrenal insufficiency may present with non-specific symptoms and signs such as nausea, vomiting, anorexia, fatigue, weakness, dizziness, and low blood pressure. Advise patients to seek medical attention if they experience a constellation of these symptoms [see Warnings and Precautions (5.7)].
Anaphylaxis
Inform patients that anaphylaxis has been reported with buprenorphine. Advise patients how to recognize such a reaction and when to seek medical attention [see Warnings and Precautions (5.10)].
Latex Allergy
The BRIXADI needle cap is synthetically derived from natural rubber latex which may cause allergic reactions in latex-sensitive individuals [see Warnings and Precautions (5.10)].
Dependence and Withdrawal
Inform patients that BRIXADI can cause drug dependence and that withdrawal signs and symptoms may occur when the medication is discontinued [see Warnings and Precautions (5.11)].
Driving or Operating Heavy Machinery
Caution patients that BRIXADI may impair the mental or physical abilities required for the performance of potentially dangerous tasks such as driving or operating hazardous machinery.
Instruct patients not to drive or operate hazardous machinery until they are reasonably certain that BRIXADI therapy does not adversely affect their ability to engage in such activities [see Warnings and Precautions (5.16)].
Orthostatic Hypotension
Inform patients that, like other opioids, BRIXADI may produce orthostatic hypotension in ambulatory individuals [see Warnings and Precautions (5.17)].
Long Duration of Action
Inform patients that they may have detectable levels of buprenorphine for a prolonged period of time after treatment with BRIXADI. Considerations of drug-drug interactions, buprenorphine effects, and analgesia may continue to be relevant for several months after the last injection [see Clinical Pharmacology (12.3)].
Drug Interactions
Instruct patients to inform their healthcare providers of any other prescription medications, over-the-counter medications, or herbal preparations that are prescribed or currently being used [see Drug Interactions (7)].
Pregnancy
Neonatal Opioid Withdrawal Syndrome
Advise women that if they are pregnant while being treated with BRIXADI, the baby may have signs of withdrawal at birth and that withdrawal is treatable [see Warnings and Precautions (5.6), Use in Specific Populations (8.1)].
Embryofetal Toxicity
Advise women of childbearing potential who become pregnant or are planning to become pregnant to consult their healthcare provider regarding the possible effects of using BRIXADI during pregnancy [see Use in Specific Populations (8.1)].
Lactation
Warn patients that buprenorphine passes into breast milk. Advise the nursing mother taking buprenorphine to monitor the infant for increased drowsiness and breathing difficulties [see Use in Specific Populations (8.2)].
Infertility
Inform patients that chronic use of opioids may cause reduced fertility. It is not known whether these effects on fertility are reversible [see Infertility (8.3)].
Emergency Analgesia
Advise patients to instruct their family members to, in the event of emergency, inform the treating physician or emergency room staff that the patient is physically dependent on an opioid and that the patient is being treated with BRIXADI [see Warnings and Precautions (5.12)].
Clinical Monitoring
Tell your patients to seek emergency attention if they have signs or symptoms of respiratory or CNS depression or overdose [see Warnings and Precautions (5.4, 5.5)].
Tell your patients not to tamper with or try to remove their depot [see Dosage and Administration (2.5)].
© 2023 Braeburn, Inc. BRIXADI™; is a trademark of Braeburn Inc.
Distributed by:
Braeburn Inc.
Plymouth Meeting, PA 19462
Manufactured by:
Pharmaceutics International, Inc. (Pii)
Cockeysville, MD 21030
05/2023