Medically reviewed by Fedorchenko Olga Valeryevna, PharmD. Last updated on 2020-04-05
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Suboxone sublingual tablet is indicated for treatment of opioid dependence and should be used as part of a complete treatment plan to include counseling and psychosocial support.
Under the Drug Addiction Treatment Act (DATA) codified at 21 U.S.C. 823(g), prescription use of this product in the treatment of opioid dependence is limited to physicians who mee certain qualifying requirements, and who have notified the Secretary of Health and Human Services (HHS) of their intent to prescribe this product for the treatment of opioid dependence and have been assigned a unique identification number that must be included on every prescription.
Important Dosage And Administration Information
Suboxone sublingual tablet is administered sublingually as a single daily dose for maintenance treatment or in divided doses for induction treatment.
The difference in bioavailability of Suboxone compared to Suboxone® tablet requires a different tablet strength to be given to the patient. One Suboxone 5.7 mg/1.4 mg sublingual tablet provides equivalent buprenorphine exposure to one Suboxone 8 mg/2 mg sublingual tablet.
Prior to induction, consideration should be given to the type of opioid dependence (i.e., long- or short-acting opioid products; see discussion that follows), the time since last opioid use, and the degree or level of opioid dependence. To avoid precipitating an opioid withdrawal syndrome, the first dose of buprenorphine/naloxone should be administered only when objective and clear signs of moderate withdrawal are evident, and divided doses should be used. It is recommended that an adequate treatment dose, titrated to clinical effectiveness, be achieved as rapidly as possible.
On Day 1, an induction dosage of up to 5.7 mg/1.4 mg Suboxone sublingual tablet is recommended. This is administered sublingually in divided doses under supervision. Clinicians should start with an initial dose of 1.4 mg/0.36 mg Suboxone sublingual tablet. The remainder of the Day 1 dose of up to 4.2 mg/1.08 mg should be divided into doses of 1 to 2 tablets of 1.4 mg/0.36 mg at 1.5 to 2 hour intervals. Some patients (e.g., those with recent exposure to buprenorphine) may tolerate up to 3 x 1.4 mg/0.36 mg Suboxone sublingual tablets as a single, second dose.
On Day 2, a single daily dose of up to 11.4 mg/2.9 mg Suboxone sublingual tablet is recommended.
All doses should be based on clinical need to control acute withdrawal symptoms and administered under supervision.
Medications should be prescribed in consideration of the frequency of visits. Provision of multiple refills is not advised early in treatment or without appropriate patient follow-up visits.
Patients Dependent On Methadone Or Long-Acting Opioid Products
Patients dependent on methadone or long-acting opioid products may be more susceptible to precipitated and prolonged withdrawal during induction than those on short-acting opioid products. Buprenorphine/naloxone combination products have not been evaluated in adequate and well-controlled studies for induction in patients who are physically dependent on long-acting opioid products and transitioning to buprenorphine treatment. Buprenorphine/naloxone combination products contain naloxone, which is absorbed in small amounts by the sublingual route and could cause worse precipitated and prolonged withdrawal. For this reason, buprenorphine monotherapy is recommended in patients taking long-acting opioids when used according to approved administration instructions. Following induction, the patient may then be transitioned to once-daily Suboxone sublingual tablet.
Patients Dependent On Heroin Or Other Short-Acting Opioid Products
Patients dependent on heroin or other short-acting opioid products may be induced with Suboxone sublingual tablet or with sublingual buprenorphine monotherapy. At treatment initiation, the dose of Suboxone should be administered when moderate objective signs of opioid withdrawal appear, not less than (6) hours after the patient last used opioids.
Suboxone sublingual tablet is indicated for maintenance treatment. The recommended target dosage of Suboxone sublingual tablet is 11.4 mg/2.9 mg buprenorphine/naloxone/day as a single daily dose.
The dosage of Suboxone sublingual tablet should be progressively adjusted in increments/decrements of 2.9 mg/0.71 mg or lower buprenorphine/naloxone to a level that holds the patient in treatment and suppresses opioid withdrawal signs and symptoms.
The maintenance dose of Suboxone sublingual tablet is generally in the range of 2.9 mg/0.71 mg buprenorphine/naloxone to 17.2 mg/4.2 mg buprenorphine/naloxone per day depending on the individual patient. Dosages higher than this have not been demonstrated to provide any clinical advantage
When determining the prescription quantity for unsupervised administration, consider the patient’s level of stability, the security of his or her home situation, and other factors likely to affect the ability to manage supplies of take-home medication.
Method Of Administration
Do not cut, crush, break, chew, or swallow Suboxone sublingual tablets. Suboxone sublingual tablet should be placed under the tongue until dissolved. The dissolve time for Suboxone varies between individuals, and the median dissolve time observed was 5 minutes. For dosages requiring more than one sublingual tablet, place all tablets in different places under the tongue at the same time. Patients should keep the tablets under the tongue until dissolved; swallowing the tablets reduces the bioavailability of the drug. Advise patients not to eat or drink anything until the tablet is completely dissolved. To ensure consistency in bioavailability, patients should follow the same manner of dosing with continued use of the product.
If a sequential mode of administration is preferred, patients should follow the same manner of dosing with continued use of the product, to ensure consistency in bioavailability.
Proper administration technique should be demonstrated to the patient.
Treatment should be initiated with supervised administration, progressing to unsupervised administration as the patient’s clinical stability permits. Suboxone sublingual tablet is subject to diversion and abuse. When determining the prescription quantity for unsupervised administration, consider the patient’s level of stability, the security of his or her home situation, and other factors likely to affect the ability to manage supplies of take-home medication.
Ideally patients should be seen at reasonable intervals (e.g., at least weekly during the first month of treatment) based upon the individual circumstances of the patient. Medication should be prescribed in consideration of the frequency of visits. Provision of multiple refills is not advised early in treatment or without appropriate patient follow-up visits. Periodic assessment is necessary to determine compliance with the dosing regimen, effectiveness of the treatment plan, and overall patient progress.
Once a stable dosage has been achieved and patient assessment (e.g., urine drug screening) does not indicate illicit drug use, less frequent follow-up visits may be appropriate. A once-monthly visit schedule may be reasonable for patients on a stable dosage of medication who are making progress toward their treatment objectives. Continuation or modification of pharmacotherapy should be based on the physician’s evaluation of treatment outcomes and objectives such as:
- Absence of medication toxicity
- Absence of medical or behavioral adverse effects
- Responsible handling of medications by the patient
- Patient’s compliance with all elements of the treatment plan (including recovery-oriented activities, psychotherapy, and/or other psychosocial modalities)
- Abstinence from illicit drug use (including problematic alcohol and/or benzodiazepine use)
If treatment goals are not being achieved, the physician should re-evaluate the appropriateness of continuing the current treatment.
Physicians will need to decide when they cannot appropriately provide further management for particular patients. For example, some patients may be abusing or dependent on various drugs, or unresponsive to psychosocial intervention such that the physician does not feel that he/she has the expertise to manage the patient. In such cases, the physician may want to assess whether to refer the patient to a specialist or more intensive behavioral treatment environment. Decisions should be based on a treatment plan established and agreed upon with the patient at the beginning of treatment.
Patients who continue to misuse, abuse, or divert buprenorphine products or other opioids should be provided with, or referred to, more intensive and structured treatment.
Patients With Hepatic Impairment
Severe hepatic impairment results in a reduced clearance of naloxone to a much greater extent than buprenorphine, and moderate hepatic impairment also results in a reduced clearance of naloxone to a greater extent than buprenorphine. Because the doses of this fixed combination product cannot be individually titrated, the combination product should generally be avoided in patients with severe hepatic impairment and may not be appropriate for patients with moderate hepatic impairment.
The decision to discontinue therapy with Suboxone sublingual tablets after a period of maintenance should be made as part of a comprehensive treatment plan. Both gradual and abrupt discontinuation of buprenorphine has been used, but the data are insufficient to determine the best method of dose taper at the end of treatment.
Switching Between Suboxone Sublingual Tablets And Other Buprenorphine/Naloxone Combination Products
For patients being switched between Suboxone sublingual tablets and other buprenorphine/naloxone products dosage adjustments may be necessary. Patients should be monitored for over-medication as well as withdrawal or other signs of under-dosing.
The differences in bioavailability of Suboxone compared to Suboxone tablet require that different tablet strengths be given to the patient. One Suboxone 5.7 mg/1.4 mg sublingual tablet provides equivalent buprenorphine exposure to one Suboxone 8 mg/2 mg sublingual tablet.
When switching between Suboxone dosage strengths and Suboxone dosage strengths the corresponding dosage strengths are:
|Suboxone sublingual tablets, including generic equivalents||Corresponding dosage strength of Suboxone sublingual tablets|
|One 2 mg/0.5 mg sublingual buprenorphine/naloxone tablet||One 1.4 mg/0.36 mg Suboxone sublingual tablet|
|4 mg/1 mg buprenorphine/naloxone taken as: ||One 2.9 mg/0.71 mg Suboxone sublingual tablet|
|One 8 mg/2 mg sublingual buprenorphine/naloxone tablet||One 5.7 mg/1.4 mg Suboxone sublingual tablet|
|12 mg/3 mg buprenorphine/naloxone, taken as: ||One 8.6 mg/2.1 mg Suboxone sublingual tablet|
|16 mg/4 mg buprenorphine/naloxone, taken as: ||One 11.4 mg/2.9 mg Suboxone sublingual tablet|
Suboxone sublingual tablet should not be administered to patients who have been shown to be hypersensitive to buprenorphine or naloxone as serious adverse reactions, including anaphylactic shock, have been reported.
Included as part of the "PRECAUTIONS" Section
Buprenorphine can be abused in a manner similar to other opioids, legal or illicit. Prescribe and dispense buprenorphine with appropriate precautions to minimize risk of misuse, abuse, or diversion, and ensure appropriate protection from theft, including in the home. Clinical monitoring appropriate to the patient’s level of stability is essential. Multiple refills should not be prescribed early in treatment or without appropriate patient follow-up visits.
Buprenorphine, particularly when taken by the IV route, in combination with benzodiazepines or other CNS depressants (including alcohol), has been associated with significant respiratory depression and death. Many, but not all, post-marketing reports regarding coma and death associated with the concomitant use of buprenorphine and benzodiazepines involved misuse by self-injection. Deaths have also been reported in association with concomitant administration of buprenorphine with other depressants such as alcohol or other CNS depressant drugs. Patients should be warned of the potential danger of self-administration of benzodiazepines or other depressants while under treatment with Suboxone sublingual tablets.
In the case of overdose, the primary management should be the re-establishment of adequate ventilation with mechanical assistance of respiration, if required. Naloxone may be of value for the management of buprenorphine overdose. Higher than normal doses and repeated administration may be necessary.
Suboxone sublingual tablets should be used with caution in patients with compromised respiratory function (e.g., chronic obstructive pulmonary disease, cor pulmonale, decreased respiratory reserve, hypoxia, hypercapnia, or pre-existing respiratory depression).
Patients receiving buprenorphine in the presence of opioid analgesics, general anesthetics, benzodiazepines, phenothiazines, other tranquilizers, sedative/hypnotics, or other CNS depressants (including alcohol) may exhibit increased CNS depression. Consider dose reduction of CNS depressants, Suboxone sublingual tablets, or both in situations of concomitant prescribing.
Unintentional Pediatric Exposure
Buprenorphine can cause fatal respiratory depression in children who are accidentally exposed to it. Store buprenorphine containing medications safely out of the sight and reach of children and destroy any unused medication appropriately.
Neonatal Opioid Withdrawal Syndrome
Neonatal opioid withdrawal syndrome (NOWS) is an expected and treatable outcome of prolonged use of opioids during pregnancy, whether that use is medically-authorized or illicit. Unlike opioid withdrawal syndrome in adults, NOWS may be life-threatening if not recognized and treated in the neonate. Healthcare professionals should observe newborns for signs of NOWS and manage accordingly.
Advise pregnant women receiving opioid addiction treatment with Suboxone of the risk of neonatal opioid withdrawal syndrome and ensure that appropriate treatment will be available. This risk must be balanced against the risk of untreated opioid addiction which often results in continued or relapsing illicit opioid use and is associated with poor pregnancy outcomes. Therefore, prescribers should discuss the importance and benefits of management of opioid addiction throughout pregnancy.
Cases of adrenal insufficiency have been reported with opioid use, more often following greater than one month of use. Presentation of adrenal insufficiency may include non-specific symptoms and signs including nausea, vomiting, anorexia, fatigue, weakness, dizziness, and low blood pressure. If adrenal insufficiency is suspected, confirm the diagnosis with diagnostic testing as soon as possible. If adrenal insufficiency is diagnosed, treat with physiologic replacement doses of corticosteroids. Wean the patient off of the opioid to allow adrenal function to recover and continue corticosteroid treatment until adrenal function recovers. Other opioids may be tried as some cases reported use of a different opioid without recurrence of adrenal insufficiency. The information available does not identify any particular opioids as being more likely to be associated with adrenal insufficiency.
Buprenorphine is a partial agonist at the mu-opioid receptor and chronic administration produces physical dependence of the opioid type, characterized by withdrawal signs and symptoms upon abrupt discontinuation or rapid taper. The withdrawal syndrome is typically milder than seen with full agonists and may be delayed in onset. Buprenorphine can be abused in a manner similar to other opioids. This should be considered when prescribing or dispensing buprenorphine in situations when the clinician is concerned about an increased risk of misuse, abuse, or diversion.
Hepatitis, Hepatic Events
Cases of cytolytic hepatitis and hepatitis with jaundice have been observed in individuals receiving buprenorphine in clinical trials and through post-marketing adverse event reports. The spectrum of abnormalities ranges from transient asymptomatic elevations in hepatic transaminases to case reports of death, hepatic failure, hepatic necrosis, hepatorenal syndrome, and hepatic encephalopathy. In many cases, the presence of pre-existing liver enzyme abnormalities, infection with hepatitis B or hepatitis C virus, concomitant usage of other potentially hepatotoxic drugs, and ongoing injecting drug use may have played a causative or contributory role. In other cases, insufficient data were available to determine the etiology of the abnormality. Withdrawal of buprenorphine has resulted in amelioration of acute hepatitis in some cases; however, in other cases no dose reduction was necessary. The possibility exists that buprenorphine had a causative or contributory role in the development of the hepatic abnormality in some cases. Liver function tests, prior to initiation of treatment is recommended to establish a baseline. Periodic monitoring of liver function during treatment is also recommended. A biological and etiological evaluation is recommended when a hepatic event is suspected. Depending on the case, Suboxone sublingual tablet may need to be carefully discontinued to prevent withdrawal signs and symptoms and a return by the patient to illicit drug use, and strict monitoring of the patient should be initiated.
Cases of hypersensitivity to buprenorphine and naloxone containing products have been reported both in clinical trials and in the post-marketing experience. Cases of bronchospasm, angioneurotic edema, and anaphylactic shock have been reported. The most common signs and symptoms include rashes, hives, and pruritus. A history of hypersensitivity to buprenorphine or naloxone is a contraindication to the use of Suboxone sublingual tablet.
Precipitation Of Opioid Withdrawal Signs And Symptoms
Because it contains naloxone, Suboxone sublingual tablet is likely to produce withdrawal signs and symptoms if misused parenterally by individuals dependent on full opioid agonists such as heroin, morphine, or methadone. Because of the partial agonist properties of buprenorphine, Suboxone sublingual tablet may precipitate opioid withdrawal signs and symptoms in such persons if administered sublingually before the agonist effects of the opioid have subsided.
Use In Opioid Naïve Patients
There have been reported deaths of opioid naive individuals who received a 2 mg dose of buprenorphine as a sublingual tablet for analgesia. Suboxone sublingual tablet is not appropriate as an analgesic.
Use In Patients With Impaired Hepatic Function
Buprenorphine/naloxone products are not recommended in patients with severe hepatic impairment and may not be appropriate for patients with moderate hepatic impairment. The doses of buprenorphine and naloxone in this fixed-dose combination product cannot be individually titrated, and hepatic impairment results in a reduced clearance of naloxone to a much greater extent than buprenorphine. Therefore, patients with severe hepatic impairment will be exposed to substantially higher levels of naloxone than patients with normal hepatic function. This may interfere with buprenorphine’s efficacy throughout treatment. In patients with moderate hepatic impairment, the differential reduction of naloxone clearance compared to buprenorphine clearance is not as great as in subjects with severe hepatic impairment. Therefore, buprenorphine/naloxone products may be used with caution for maintenance treatment in patients with moderate hepatic impairment who have initiated treatment on a buprenorphine product without naloxone. However, patients should be carefully monitored and consideration given to the possibility of naloxone interfering with buprenorphine’s efficacy.
Impairment Of Ability To Drive Or Operate Machinery
Suboxone sublingual tablet may impair the mental or physical abilities required for the performance of potentially dangerous tasks such as driving a car or operating machinery, especially during treatment induction and dose adjustment. Patients should be cautioned about driving or operating hazardous machinery until they are reasonably certain that Suboxone sublingual tablet therapy does not adversely affect his or her ability to engage in such activities.
Like other opioids, Suboxone sublingual tablets may produce orthostatic hypotension in ambulatory patients.
Elevation Of Cerebrospinal Fluid Pressure
Buprenorphine, like other opioids, may elevate cerebrospinal fluid pressure and should be used with caution in patients with head injury, intracranial lesions, and other circumstances when cerebrospinal pressure may be increased. Buprenorphine can produce miosis and changes in the level of consciousness that may interfere with patient evaluation.
Elevation Of Intracholedochal Pressure
Buprenorphine has been shown to increase intracholedochal pressure, as do other opioids, and thus should be administered with caution to patients with dysfunction of the biliary tract.
Effects In Acute Abdominal Conditions
As with other opioids, buprenorphine may obscure the diagnosis or clinical course of patients with acute abdominal conditions.
Suboxone sublingual tablet should be administered with caution in debilitated patients and those with myxedema or hypothyroidism, adrenal cortical insufficiency (e.g., Addison's disease); CNS depression or coma; toxic psychoses; prostatic hypertrophy or urethral stricture; acute alcoholism; delirium tremens; or kyphoscoliosis.
Patient Counseling Information
See FDA-approved patient labeling. (PATIENT INFORMATION)
Before initiating treatment with Suboxone sublingual tablets, explain the points listed below to caregivers and patients. Instruct patients to read the Medication Guide each time Suboxone is dispensed because new information may be available.
- Patients should be warned that it is extremely dangerous to self-administer non-prescribed benzodiazepines or other CNS depressants (including alcohol) while taking Suboxone sublingual tablets. Patients prescribed benzodiazepines or other CNS depressants should be cautioned to use them only as directed by their physician.
- Patients should be advised that Suboxone sublingual tablets contain an opioid that can be a target for people who abuse prescription medications or street drugs. Patients should be cautioned to keep their tablets in a safe place, and to protect them from theft.
- Patients should be instructed to keep Suboxone sublingual tablets in a secure place, out of the sight and reach of children. Accidental or deliberate ingestion by a child may cause respiratory depression that can result in death. Patients should be advised that if a child is exposed to Suboxone sublingual tablets, medical attention should be sought immediately.
- Inform patients that Suboxone 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.
- Inform patients that Suboxone 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.
- Patients should be advised never to give Suboxone sublingual tablets to anyone else, even if he or she has the same signs and symptoms. It may cause harm or death.
- Patients should be advised that selling or giving away this medication is against the law.
- Patients should be cautioned that Suboxone sublingual tablets may impair the mental or physical abilities required for the performance of potentially dangerous tasks such as driving or operating machinery. Caution should be taken especially during drug induction and dose adjustment and until individuals are reasonably certain that buprenorphine therapy does not adversely affect their ability to engage in such activities.
- Patients should be advised not to change the dosage of Suboxone sublingual tablets without consulting their physician.
- Patients should be advised to take Suboxone sublingual tablets once a day, after induction.
- Patients should be advised that if they miss a dose of Suboxone they should take it as soon as they remember. If it is almost time for the next dose, they should skip the missed dose and take the next dose at the regular time.
- Patients should be informed that Suboxone sublingual tablets can cause drug dependence and that withdrawal signs and symptoms may occur when the medication is discontinued.
- Patients seeking to discontinue treatment with buprenorphine for opioid dependence should be advised to work closely with their physician on a tapering schedule and should be apprised of the potential to relapse to illicit drug use associated with discontinuation of opioid agonist/partial agonist medication-assisted treatment.
- Patients should be cautioned that, like other opioids, Suboxone sublingual tablets may produce orthostatic hypotension in ambulatory individuals.
- Patients should inform their physician if any other prescription medications, over-the-counter medications, or herbal preparations are prescribed or currently being used.
- Advise women that if they are pregnant while being treated with Suboxone, the baby may have signs of withdrawal at birth and that withdrawal is treatable.
- Advise women who are breastfeeding to monitor the infant for drowsiness and difficulty breathing.
- Inform patients that chronic use of opioids may cause reduced fertility. It is not known whether these effects on fertility are reversible.
- Patients should inform their family members that, in the event of emergency, the treating physician or emergency room staff should be informed that the patient is physically dependent on an opioid and that the patient is being treated with Suboxone sublingual tablets.
- Refer to the Medication Guide for additional information regarding the counseling information.
Disposal Of Unused Suboxone Sublingual Tablets
Unused Suboxone sublingual tablets should be disposed of as soon as they are no longer needed. Unused tablets should be flushed down the toilet.
Carcinogenesis, Mutagenesis, Impairment Of Fertility
Suboxone has been shown to have differences in bioavailability compared to other buprenorphine/naloxone-containing sublingual products. The exposure margins listed below are based on body surface area comparisons (mg/m2) to the recommended human sublingual dose of 16 mg buprenorphine via Suboxone, which is equivalent to a human sublingual dose of 11.4 mg buprenorphine via Suboxone.
A carcinogenicity study of buprenorphine/naloxone (4:1 ratio of the free bases) was performed in Alderley Park rats. Buprenorphine/naloxone was administered in the diet at doses of approximately 7 mg/kg/day, 31 mg/kg/day, and 123 mg/kg/day for 104 weeks (estimated exposure was approximately 4, 18, and 44 times the recommended human sublingual dose based on buprenorphine AUC comparisons). A statistically significant increase in Leydig cell adenomas was observed in all dose groups. No other drug-related tumors were noted.
Carcinogenicity studies of buprenorphine were conducted in Sprague-Dawley rats and CD-1 mice. Buprenorphine was administered in the diet to rats at doses of 0.6 mg/kg/day, 5.5 mg/kg/day, and 56 mg/kg/day (estimated exposure was approximately 0.4, 3, and 35 times the recommended human sublingual dose) for 27 months. As in the buprenorphine/naloxone carcinogenicity study in rat, statistically significant dose-related increases 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 (estimated exposure was approximately 30 times the recommended human sublingual dose).
The 4:1 combination of buprenorphine and naloxone was not mutagenic in a bacterial mutation assay (Ames test) using four strains of S. typhimurium and two strains of E. coli. The combination was not clastogenic in an in vitro cytogenetic assay in human lymphocytes or in an IV micronucleus test in the rat.
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 [3H]thymidine, and positive in unscheduled DNA synthesis (UDS) test using testicular cells from mice.
Impairment Of Fertility
Dietary administration of buprenorphine in the rat at dose levels of 500 ppm or greater (equivalent to approximately 47 mg/kg/day or greater; estimated exposure approximately 28 times the recommended human sublingual dose) produced a reduction in fertility demonstrated by reduced female conception rates. A dietary dose of 100 ppm (equivalent to approximately 10 mg/kg/day; estimated exposure approximately 6 times the recommended human sublingual dose) had no adverse effect on fertility.
Use In Specific Populations
The data on use of buprenorphine, the active ingredient in Suboxone, 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 buprenorphine that were not designed appropriately to assess the risk of major malformations. Observational studies have reported on congenital malformations among buprenorphine-exposed pregnancies, but were also not designed appropriately to assess the risk of congenital malformations specifically due to buprenorphine exposure. The extremely limited data on sublingual naloxone exposure in pregnancy are not sufficient to evaluate a drug-associated risk.
Reproductive and developmental studies in rats and rabbits identified adverse events at clinically relevant and higher doses. Embryofetal death was observed in both rats and rabbits administered buprenorphine during the period of organogenesis at doses approximately 6 and 0.3 times, respectively, the human sublingual dose of 16 mg/day of buprenorphine. Pre-and postnatal development studies in rats demonstrated increased neonatal deaths at 0.3 times and above and dystocia at approximately 3 times the human sublingual dose of 16 mg/day of buprenorphine. No clear teratogenic effects were seen when buprenorphine was administered during organogenesis with a range of doses equivalent to or greater than the human sublingual dose of 16 mg/day of buprenorphine. However, increases in skeletal abnormalities were noted in rats and rabbits administered buprenorphine daily during organogenesis at doses approximately 0.6 times and approximately equal to the human sublingual dose of 16 mg/day 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.
The estimated background risk of major birth defects and miscarriage for the indicated population are unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes 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.
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 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 Suboxone.
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.
Labor or Delivery
Opioid-dependent women on buprenorphine maintenance therapy may require additional analgesia during labor.
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 (“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.
Suboxone has been shown to have differences in bioavailability compared to other buprenorphine/naloxone-containing sublingual products. The exposure margins listed below are based on body surface area comparisons (mg/m2) to the recommended human sublingual dose of 16 mg buprenorphine via Suboxone, which is equivalent to a human sublingual dose of 11.4 mg buprenorphine via Suboxone.
Effects on embryo-fetal development were studied in Sprague-Dawley rats and Russian white rabbits following oral (1:1) and intramuscular (IM) (3:2) administration of mixtures of buprenorphine and naloxone during the period of organogenesis. Following oral administration to rats no teratogenic effects were observed at buprenorphine doses up to 250 mg/kg/day (estimated exposure approximately 150 times the human sublingual dose of 16 mg).
Following oral administration to rabbits, no teratogenic effects were observed at buprenorphine doses up to 40 mg/kg/day (estimated exposure approximately 50 times the human sublingual dose of 16 mg). No definitive drug-related teratogenic effects were observed in rats and rabbits at IM doses up to 30 mg/kg/day (estimated exposure approximately 20 times and 35 times, respectively, the human sublingual dose of 16 mg). 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. 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 (estimated exposure approximately 6 times the human sublingual dose of 16 mg).
In the rabbit, increased post-implantation losses occurred at an oral dose of 40 mg/kg/day. 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.
Buprenorphine was not teratogenic in rats or rabbits after IM or subcutaneous (SC) doses up to 5 mg/kg/day (estimated exposure was approximately 3 and 6 times, respectively, the human sublingual dose of 16 mg), after IV doses up to 0.8 mg/kg/day (estimated exposure was approximately 0.5 times and equal to, respectively, the human sublingual dose of 16 mg), or after oral doses up to 160 mg/kg/day in rats (estimated exposure was approximately 95 times the human sublingual dose of 16 mg) and 25 mg/kg/day in rabbits (estimated exposure was approximately 30 times the human sublingual dose of 16 mg). 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 (estimated exposure was approximately 0.6 times the human sublingual dose of 16 mg), but were not observed at oral doses up to 160 mg/kg/day.
Increases in skeletal abnormalities in rabbits after IM administration of 5 mg/kg/day (estimated exposure was approximately 6 times the human sublingual dose of 16 mg) or oral administration of 1 mg/kg/day or greater (estimated exposure was approximately equal to the human sublingual dose of 16 mg) were not statistically significant.
In rabbits, buprenorphine produced statistically significant pre-implantation losses at oral doses of 1 mg/kg/day or greater and post-implantation losses that were statistically significant at IV doses of 0.2 mg/kg/day or greater (estimated exposure approximately 0.3 times the human sublingual dose of 16 mg).
Dystocia was noted in pregnant rats treated intramuscularly with buprenorphine during gestation and lactation at 5 mg/kg/day (approximately 3 times the human sublingual dose of 16 mg). Fertility, 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 (approximately 0.5 times the human sublingual dose of 16 mg), after IM doses of 0.5 mg/kg/day and up (approximately 0.3 times the human sublingual dose of 16 mg), and after SC doses of 0.1 mg/kg/day and up (approximately 0.06 times the human sublingual dose of 16 mg). 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 (approximately 50 times the human sublingual dose of 16 mg).
Based on two studies in 13 lactating women, maintained on buprenorphine treatment, buprenorphine and its metabolite norbuprenorphine were present in low levels in human milk and infant urine, and available data have not shown adverse reactions in breastfed infants. There are no data on the combination product buprenorphine/naloxone in breastfeeding, however oral absorption of naloxone is limited. Caution should be exercised when Suboxone is administered to a nursing woman. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for Suboxone and any potential adverse effects on the breastfed child from the drug or from the underlying maternal condition.
Advise the breastfeeding women taking buprenorphine products to monitor the infant for increased drowsiness and breathing difficulties.
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 med
Clinical Trials Experience
Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.
Suboxone for use as initial treatment was evaluated in two clinical trials that had identical, blinded, two-day induction phases, comparing Suboxone to generic buprenorphine. On the first day, subjects received an initial dose of Suboxone 1.4 mg/0.36 mg or generic buprenorphine 2 mg, followed by Suboxone 4.2 mg/1.08 mg or generic buprenorphine 6 mg 1.5 hours later. In total, safety data were available for 538 opioid-dependent subjects exposed to Suboxone (buprenorphine/naloxone) sublingual tablets when used for initial treatment.
Table 1. Adverse Reactions in ≥ 5% of Patients During the Induction Phase by System Organ Class and Preferred Term (Safety Population)
|System Organ Class |
|Generic BUP |
|Patients with any |
|139 (26%)||136 (26%)||275 (26%)|
|64 (12%)||60 (11%)||124 (12%)|
|Nausea||29 (5%)||36 (7%)||65 (6%)|
|Vomiting||25 (5%)||26 (5%)||51 (5%)|
|Nervous System |
|48 (9%)||44 (8%)||92 (9%)|
|Headache||36 (7%)||35 (7%)||71 (7%)|
|BUP = buprenorphine |
Suboxone = buprenorphine/naloxone
The safety of buprenorphine/naloxone for longer-term use (up to 16 weeks of treatment) was evaluated in previous studies in 497 opioid-dependent subjects. The prospective evaluation of buprenorphine/naloxone was supported by clinical trials using buprenorphine tablets without naloxone and other trials using buprenorphine sublingual solutions. In total, safety data were available from 3214 opioid-dependent subjects exposed to buprenorphine at doses in the range used in treatment of opioid addiction. See Table 2.
Table 2. Adverse Events > 5% by Body System and Treatment Group in a 4-week Study
|Body System / Adverse Event (COSTART Terminology)||N (%)||N (%)|
|Buprenorphine/ naloxone 16 mg/day |
|Body as a Whole|
|Asthenia||7 (7%)||7 (7%)|
|Chills||8 (8%)||8 (8%)|
|Headache||39 (37%)||24 (22%)|
|Infection||6 (6%)||7 (7%)|
|Pain||24 (22%)||20 (19%)|
|Pain Abdomen||12 (11%)||7 (7%)|
|Pain Back||4 (4%)||12 (11%)|
|Withdrawal Syndrome||27 (25%)||40 (37%)|
|Vasodilation||10 (9%)||7 (7%)|
|Constipation||13 (12%)||3 (3%)|
|Diarrhea||4 (4%)||16 (15%)|
|Nausea||16 (15%)||12 (11%)|
|Vomiting||8 (8%)||5 (5%)|
|Insomnia||15 (14%)||17 (16%)|
|Rhinitis||5 (5%)||14 (13%)|
|Skin and Appendages|
|Sweating||15 (14%)||11 (10%)|
The adverse event profile of buprenorphine was also characterized in the dose-controlled study of buprenorphine solution, over a range of doses in four months of treatment. Table 3 shows adverse events reported by at least 5% of subjects in any dose group in the dose-controlled study.
Table 3. Adverse Events (≥ 5%) by Body System and Treatment Group in a 16-week Study
|Body System /Adverse Event (COSTART Terminology)||Buprenorphine dose*|
|Very Low* |
|N (%)||N (%)||N (%)||N (%)||N (%)|
|*Sublingual solution. Doses in this table cannot necessarily be delivered in tablet form, but for comparison purposes: |
"Very low" dose (1 mg solution) would be less than a Suboxone tablet dose of 2 mg
"Low" dose (4 mg solution) approximates a 6 mg Suboxone tablet dose
"Moderate" dose (8 mg solution) approximates a 12 mg Suboxone tablet dose
"High" dose (16 mg solution) approximates a 24 mg Suboxone tablet dose
|Body as a Whole|
|Abscess||9 (5%)||2 (1%)||3 (2%)||2 (1%)||16 (2%)|
|Asthenia||26 (14%)||28 (16%)||26 (14%)||24 (13%)||104 (14%)|
|Chills||11 (6%)||12 (7%)||9 (5%)||10 (6%)||42 (6%)|
|Fever||7 (4%)||2 (1%)||2 (1%)||10 (6%)||21 (3%)|
|Flu Syndrome.||4 (2%)||13 (7%)||19 (10%)||8 (4%)||44 (6%)|
|Headache||51 (28%)||62 (34%)||54 (29%)||53 (29%)||220 (30%)|
|Infection||32 (17%)||39 (22%)||38 (20%)||40 (22%)||149 (20%)|
|Injury Accidental||5 (3%)||10 (6%)||5 (3%)||5 (3%)||25 (3%)|
|Pain||47 (26%)||37 (21%)||49 (26%)||44 (24%)||177 (24%)|
|Pain Back||18 (10%)||29 (16%)||28 (15%)||27 (15%)||102 (14%)|
|Withdrawal Syndrome||45 (24%)||40 (22%)||41 (22%)||36 (20%)||36 (20%)|
|Constipation||10 (5%)||23 (13%)||23 (12%)||26 (14%)||82 (11%)|
|Diarrhea||19 (10%)||8 (4%)||9 (5%)||4 (2%)||40 (5%)|
|Dyspepsia||6 (3%)||10 (6%)||4 (2%)||4 (2%)||24 (3%)|
|Nausea||12 (7%)||22 (12%)||23 (12%)||18 (10%)||75 (10%)|
|Vomiting||8 (4%)||6 (3%)||10 (5%)||14 (8%)||38 (5%)|
|Anxiety||22 (12%)||24 (13%)||20 (11%)||25 (14%)||91 (12%)|
|Depression||24 (13%)||16 (9%)||25 (13%)||18 (10%)||83 (11%)|
|Dizziness||4 (2%)||9 (5%)||7 (4%)||11 (6%)||31 (4%)|
|Insomnia||42 (23%)||50 (28%)||43 (23%)||51 (28%)||186 (25%)|
|Nervousness||12 (7%)||11 (6%)||10 (5%)||13 (7%)||46 (6%)|
|Somnolence||5 (3%)||13 (7%)||9 (5%)||11 (6%)||38 (5%)|
|Cough Increase||5 (3%)||11 (6%)||6 (3%)||4 (2%)||26 (4%)|
|Pharyngitis||6 (3%)||7 (4%)||6 (3%)||9 (5%)||28 (4%)|
|Rhinitis||27 (15%)||16 (9%)||15 (8%)||21 (12%)||79 (11%)|
|Skin and Appendages|
|Sweat||23 (13%)||21 (12%)||20 (11%)||23 (13%)||87 (12%)|
|Runny Eyes||13 (7%)||9 (5%)||6 (3%)||6 (3%)||34 (5%)|
The following adverse reactions have been identified during post-approval use of buprenorphine and naloxone sublingual tablets. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate a causal relationship to drug exposure.
The most frequently reported post-marketing adverse event not observed in clinical trials was peripheral edema.
Serotonin syndrome: Cases of serotonin syndrome, a potentially life-threatening condition, have been reported during concomitant use of opioids with serotonergic drugs.
Adrenal insufficiency: Cases of adrenal insufficiency have been reported with opioid use, more often following greater than one month of use.
Anaphylaxis: Anaphylaxis has been reported with ingredients contained in Suboxone.
Androgen deficiency: Cases of androgen deficiency have occurred with chronic use of opioids.
The manifestations of acute overdose include pinpoint pupils, sedation, hypotension, respiratory depression, and death.
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 employed as indicated.
In the case of overdose, the primary management should be the re-establishment of adequate ventilation with mechanical assistance of respiration, if required. Naloxone may be of value for the management of buprenorphine overdose. Higher than normal doses and repeated administration may be necessary. The long duration of action of Suboxone should be taken into consideration when determining the length of treatment and medical surveillance needed to reverse the effects of an overdose. Insufficient duration of monitoring may put patients at risk.
Suboxone has been shown to have different bioavailability compared to Suboxone tablet. One Suboxone 5.7 mg/1.4 mg tablet provides equivalent buprenorphine exposure and 12% lower naloxone exposure to one Suboxone 8 mg/2 mg tablet. The pharmacodynamic information of other currently marketed buprenorphine/naloxone-containing sublingual products is not directly comparable on a mg basis to Suboxone.
Comparisons of buprenorphine to full opioid agonists such as methadone and hydromorphone suggest that sublingual buprenorphine produces typical opioid agonist effects which are limited by a ceiling effect.
In opioid-experienced subjects who were not physically dependent, acute sublingual doses of Suboxone tablets produced opioid agonist effects which reached a maximum between doses of 8 mg/2 mg and 16 mg/4 mg buprenorphine/naloxone.
Opioid agonist ceiling-effects were also observed in a double-blind, parallel group, dose-ranging comparison of single doses of buprenorphine sublingual solution (1 mg, 2 mg, 4 mg, 8 mg, 16 mg, or 32 mg), placebo and a full agonist control at various doses. The treatments were given in ascending dose order at intervals of at least one week to 16 opioid-experienced subjects who were not physically dependent. Both active drugs produced typical opioid agonist effects. For all measures for which the drugs produced an effect, buprenorphine produced a dose-related response. However, in each case, there was a dose that produced no further effect. In contrast, the highest dose of the full agonist control always produced the greatest effects. Agonist objective rating scores remained elevated for the higher doses of buprenorphine (8 mg- 32 mg) longer than for the lower doses and did not return to baseline until 48 hours after drug administration. The onset of effects appeared more rapidly with buprenorphine than with the full agonist control, with most doses nearing peak effect after 100 minutes for buprenorphine compared to 150 minutes for the full agonist control.
Buprenorphine in IV (2 mg, 4 mg, 8 mg, 12 mg and 16 mg) and sublingual (12 mg) doses has 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 dependence. 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 mg, 2 mg, 4 mg, 8 mg, 16 mg, or 32 mg) and oral methadone (15 mg, 30 mg, 45 mg, 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.
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..
Effect Of Naloxone
Physiologic and subjective effects following acute sublingual administration of buprenorphine tablets and Suboxone tablets were similar at equivalent dose levels of buprenorphine. Naloxone had no clinically significant effect when administered by the sublingual route, although blood levels of the drug were measurable. Buprenorphine/naloxone, when administered sublingually to an opioid-dependent cohort, was recognized as an opioid agonist, whereas when administered intramuscularly, combinations of buprenorphine with naloxone produced opioid antagonist actions similar to naloxone. This finding suggests that the naloxone in buprenorphine/naloxone tablets may deter injection of buprenorphine/naloxone tablets by persons with active substantial heroin or other full mu-opioid dependence. However, clinicians should be aware that some opioid-dependent persons, particularly those with a low level of full mu-opioid physical dependence or those whose opioid physical dependence is predominantly to buprenorphine, abuse buprenorphine/naloxone combinations by the intravenous or intranasal route. In methadone-maintained patients and heroin-dependent subjects, IV administration of buprenorphine/naloxone combinations precipitated opioid withdrawal signs and symptoms and was perceived as unpleasant and dysphoric. In morphine-stabilized subjects, intravenously administered combinations of buprenorphine with naloxone produced opioid antagonist and withdrawal signs and symptoms that were ratio-dependent; the most intense withdrawal signs and symptoms were produced by 2:1 and 4:1 ratios, less intense by an 8:1 ratio.
Plasma levels of buprenorphine and naloxone increased with the sublingual dose of Suboxone sublingual tablet. There was wide inter-patient variability in the sublingual absorption of buprenorphine and naloxone, but within subjects the variability was low. Both Cmax and AUC of buprenorphine increased with the increase in dose (in the range of 1.4 mg to 11.4 mg), although the increase was not directly dose-proportional. Naloxone did not affect the pharmacokinetics of buprenorphine.
Suboxone has been shown to have different bioavailability compared to Suboxone tablet. One Suboxone 5.7 mg/1.4 mg tablet provides equivalent buprenorphine exposure and 12% lower naloxone exposure to one Suboxone 8 mg/2 mg tablet.
Buprenorphine is approximately 96% protein bound, primarily to alpha and beta globulin.
Naloxone is approximately 45% protein bound, primarily to albumin.
Buprenorphine has a mean elimination half-life from plasma ranging from 24 to 42 hours and naloxone has a mean elimination half-life from plasma ranging from 2 to 12 hours.
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. Naloxone undergoes direct glucuronidation to naloxone-3-glucuronide as well as N-dealkylation, and reduction of the 6-oxo group.
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 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).