Buprenorphine Hydrochloride - Buprenorphine Hydrochloride injection prescribing information
WARNING: SERIOUS AND LIFE-THREATENING RISKS FROM USE OF BUPRENORPHINE
Addiction, Abuse, and Misuse
Because the use of buprenorphine exposes patients and other users to the risks of opioid addiction, abuse, and misuse, which can lead to overdose and death, assess each patient's risk prior to prescribing and reassess all patients regularly for the development of these behaviors and conditions (see WARNINGS ) .
Life-Threatening Respiratory Depression
Serious, life-threatening, or fatal respiratory depression may occur with use of buprenorphine, especially during initiation or following a dosage increase. To reduce the risk of respiratory depression, proper dosing and titration of buprenorphine are essential (see WARNINGS ) .
Risks From Concomitant Use With Benzodiazepines Or Other CNS Depressants
C oncomitant use of opioids with benzodiazepines or other central nervous system (CNS) depressants, including alcohol, may result in profound sedation, respiratory depression, coma, and death. Reserve concomitant prescribing of buprenorphine and benzodiazepines or other CNS depressants for use in patients for whom alternative treatment options are inadequate (see WARNINGS , PRECAUTIONS ) .
Neonatal Opioid Withdrawal Syndrome (NOWS)
Advise pregnant women using opioids for an extended period of time of the risk of Neonatal Opioid Withdrawal Syndrome, which may be life-threatening if not recognized and treated. Ensure that management by neonatology experts will be available at delivery (see WARNINGS ) .
INDICATIONS AND USAGE
Buprenorphine hydrochloride injection is indicated for the management of pain severe enough to require an opioid analgesic and for which alternate treatments are inadequate.
Limitations of Use:
Because of the risks of addiction, abuse, misuse, overdose, and death which can occur at any dosage or duration and persist over the course of therapy [see WARNINGS ] , reserve opioid analgesics, including buprenorphine, for use in patients for whom alternative treatment options are ineffective, not tolerated, or would be otherwise inadequate to provide sufficient management of pain.
DOSAGE AND ADMINISTRATION
- Buprenorphine should be prescribed only by healthcare professionals who are knowledgeable about the use of opioids and how to mitigate the associated risks.
- Use the lowest effective dosage for the shortest duration of time consistent with individual patient treatment goals [see WARNINGS ]. Because the risk of overdose increases as opioid doses increase, reserve titration to higher doses of buprenorphine for patients in whom lower doses are insufficiently effective and in whom the expected benefits of using a higher dose opioid clearly outweigh the substantial risks.
- Many acute pain conditions (e.g., the pain that occurs with a number of surgical procedures or acute musculoskeletal injuries) require no more than a few days of an opioid analgesic. Clinical guidelines on opioid prescribing for some acute pain conditions are available.
- There is variability in the opioid analgesic dose and duration needed to adequately manage pain due both to the cause of pain and to individual patient factors. Initiate the dosing regimen for each patient individually, taking into account the patient's underlying cause and severity of pain, prior analgesic treatment and response, and risk factors for addiction, abuse, and misuse [see WARNINGS ].
- Respiratory depression can occur at any time during opioid therapy, especially when initiating and following dosage increases with buprenorphine. Consider this risk when selecting an initial dose and when making dose adjustments [see WARNINGS ] .
- Inspect buprenorphine for particulate matter and discoloration prior to administration.
Dosing
Adults and Pediatric Patients over 12 years of age
The initial starting dose is 1 mL buprenorphine hydrochloride (0.3 mg buprenorphine) given by deep intramuscular or slow (over at least 2 minutes) intravenous injection at up to 6-hour intervals, as needed.
Repeat once (up to 0.3 mg) if required, 30 to 60 minutes after initial dosage, giving consideration to previous dose pharmacokinetics, and thereafter only as needed. In high-risk patients (e.g., elderly, debilitated, presence of respiratory disease, etc.) and/or in patients where other CNS depressants are present, such as in the immediate postoperative period, the dose should be limited to the minimum required.
Extra caution should be exercised with the intravenous route of administration, particularly with the initial dose. Occasionally, it may be necessary to administer single doses of up to 0.6 mg to adults depending on the severity of the pain and the response of the patient. This dose should only be given I.M. and only to adult patients who are not in a high risk category [see WARNINGS and PRECAUTIONS ]. At this time, there are insufficient data to recommend single doses greater than 0.6 mg for long-term use.
Pediatric Patients
Buprenorphine hydrochloride injection has been used in pediatric patients 2 to 12 years of age at doses between 2 to 6 micrograms/kg of body weight given every 4 to 6 hours. There is insufficient experience to recommend a dose in infants below the age of two years, single doses greater than 6 micrograms/kg of body weight, or the use of a repeat or second dose at 30 to 60 minutes (such as is used in adults). Since there is some evidence that not all pediatric patients clear buprenorphine faster than adults, fixed interval or "round-the-clock" dosing should not be undertaken until the proper inter-dose interval has been established by clinical observation of the child. Healthcare providers should recognize that, as with adults, some pediatric patients may not need to be remedicated for 6 to 8 hours.
Safety and Handling
Buprenorphine hydrochloride injection is supplied in sealed vials and poses no known environmental risk to healthcare providers. Accidental dermal exposure should be treated by removal of any contaminated clothing and rinsing the affected area with water.
Buprenorphine is a potent opioid and, like all drugs of this class, has been associated with abuse and dependence among healthcare providers. To control the risk of diversion, it is recommended that measures appropriate to the healthcare setting be taken to provide rigid accounting, control of wastage, and restriction of access.
Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.
CONTRAINDICATIONS
Buprenorphine hydrochloride is contraindicated in patients with:
Significant respiratory depression [see WARNINGS ].
Acute or severe bronchial asthma in an unmonitored setting or in the absence of resuscitative equipment [see WARNINGS ].
Known or suspected gastrointestinal obstruction, including paralytic ileus [see WARNINGS ].
- Hypersensitivity to buprenorphine (e.g., anaphylaxis) or any other ingredient in buprenorphine hydrochloride injection [see WARNINGS ].
ADVERSE REACTIONS
Postmarketing Experience
The most frequent side effect in clinical studies involving 1,133 patients was sedation which occurred in approximately two-thirds of the patients. Although sedated, these patients could easily be aroused to an alert state.
Other less frequent adverse reactions occurring in 5 to 10% of the patients were: | |
Nausea | Dizziness/Vertigo |
Occurring in 1 to 5% of the patients: | |
Sweating | Headache |
Hypotension | Nausea/Vomiting |
Vomiting | Hypoventilation |
Miosis | |
The following adverse reactions were reported to have occurred in less than 1% of the patients:
CNS Effect: confusion, blurred vision, euphoria, weakness/fatigue, dry mouth, nervousness, depression, slurred speech, paresthesia.
Cardiovascular: hypertension, tachycardia, bradycardia.
Gastrointestinal: constipation.
Respiratory: dyspnea, cyanosis.
Dermatological: pruritus.
Ophthalmological: diplopia, visual abnormalities.
Miscellaneous: injection site reaction, urinary retention, dreaming, flushing/warmth, chills/cold, tinnitus, conjunctivitis, Wenckebach block, and psychosis.
Other effects observed infrequently include malaise, hallucinations, depersonalization, coma, dyspepsia, flatulence, apnea, rash, amblyopia, tremor, and pallor.
The following reactions have been reported to occur rarely: loss of appetite, dysphoria/agitation, diarrhea, urticaria, and convulsions/lack of muscle coordination.
Allergic Reactions: Cases of acute and chronic hypersensitivity to buprenorphine have been reported both in clinical trials and in the postmarketing experience of buprenorphine hydrochloride injection and other buprenorphine-containing products. The most common signs and symptoms include rashes, hives, and pruritus. Cases of bronchospasm, angioneurotic edema, and anaphylactic shock have been reported. A history of hypersensitivity to buprenorphine is a contraindication to buprenorphine hydrochloride.
In the United Kingdom, buprenorphine hydrochloride was made available under monitored release regulation during the first year of sale, and yielded data from 1,736 physicians on 9,123 patients (17,120 administrations). Data on 240 children under the age of 18 years were included in this monitored release program. No important new adverse effects attributable to buprenorphine hydrochloride were observed.
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.
Androgen deficiency : Cases of androgen deficiency have occurred with use of opioids for an extended period of time (see CLINICAL PHARMACOLOGY: Pharmacodynamics ) .
Hyperalgesia and Allodynia: Cases of hyperalgesia and allodynia have been reported with opioid therapy of any duration ( see WARNINGS ) .
Hypoglycemia: Cases of hypoglycemia have been reported in patients taking opioids. Most reports were in patients with at least one predisposing risk factor (e.g., diabetes).
Opioid-induced esophageal dysfunction (OIED): Cases of OIED have been reported in patients taking opioids and may occur more frequently in patients taking higher doses of opioids, and/or in patients taking opioids longer term (see WARNINGS ) .
Adverse Reactions from Observational Studies
A prospective, observational cohort study estimated the risks of addiction, abuse, and misuse in patients initiating long-term use of Schedule II opioid analgesics between 2017 and 2021. Study participants included in one or more analyses had been enrolled in selected insurance plans or health systems for at least one year, were free of at least one outcome at baseline,
completed a minimum number of follow-up assessments, and either: 1) filled multiple extended-release/long-acting opioid analgesic prescriptions during a 90-day period (n=978); or 2) filled any Schedule II opioid analgesic prescriptions covering at least 70 of 90 days (n=1,244). Those included also had no dispensing of the qualifying opioids in the previous 6 months.
Over 12 months:
- approximately 1% to 6% of participants across the two cohorts newly met criteria for addiction, as assessed with two validated interview-based measures of moderate-to-severe opioid use disorder based on Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria, and
- approximately 9% and 22% of participants across the two cohorts newly met criteria for prescription opioid abuse and misuse [defined in DRUG ABUSE AND DEPENDENCE ], respectively, as measured with a validated self-reported instrument.
A retrospective, observational cohort study estimated the risk of opioid-involved overdose or opioid overdose-related death in patients with new long-term use of Schedule II opioid analgesics from 2006 through 2016 (n=220,249). Included patients had been enrolled in either one of two
commercial insurance programs, one managed care program, or one Medicaid program for at least 9 months. New long-term use was defined as having Schedule II opioid analgesic prescriptions covering at least 70 days’ supply over the 3 months prior to study entry and none during the preceding 6 months. Patients were excluded if they had an opioid-involved
overdose in the 9 months prior to study entry. Overdose was measured using a validated medical code-based algorithm with linkage to the National Death Index database. The 5-year cumulative incidence estimates for opioid-involved overdose or opioid overdose-related death ranged from
approximately 1.5% to 4% across study sites, counting only the first event during follow-up. Approximately 17% of first opioid overdoses observed over the entire study period (5-11 years, depending on the study site) were fatal. Higher baseline opioid dose was the strongest and most consistent predictor of opioid-involved overdose or opioid overdose-related death.
Study exclusion criteria may have selected patients at lower risk of overdose, and substantial loss to follow-up (approximately 80%) also may have biased estimates.
The risk estimates from the studies described above may not be generalizable to all patients receiving opioid analgesics, such as those with exposures shorter or longer than the duration evaluated in the studies.
For medical advice about adverse reactions contact your medical professional. To report SUSPECTED ADVERSE REACTIONS, contact Par Health at 1-800-828-9393 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.
Drug Interactions
Clinically significant drug interactions with Buprenorphine Hydrochloride Injection
Benzodiazepines and Other Central Nervous System (CNS) Depressants | |
Clinical Impact: | Due to additive pharmacologic effect, the concomitant use of benzodiazepines or other CNS depressants, including alcohol, can increase the risk of hypotension, respiratory depression, profound sedation, coma, and death. |
Intervention: | Reserve concomitant prescribing of these drugs for use in patients for whom alternative treatment options are inadequate. Limit dosages and durations to the minimum required. Monitor patients closely for signs of respiratory depression and sedation [see WARNINGS] . |
Examples: | Benzodiazepines and other sedatives/hypnotics, anxiolytics, tranquilizers, muscle relaxants, general anesthetics, antipsychotics, gabapentinoids [gabapentin or pregabalin], and other opioids, alcohol. |
Inhibitors of CYP3A4 | |
Clinical Impact: | The concomitant use of buprenorphine and CYP3A4 inhibitors can increase the plasma concentration of buprenorphine, resulting in increased or prolonged opioid effects, particularly when an inhibitor is added after a stable dose of buprenorphine is achieved. After stopping a CYP3A4 inhibitor, as the effects of the inhibitor decline, the buprenorphine plasma concentration will decrease [see CLINICAL PHARMACOLOGY: Pharmacokinetics], potentially resulting in decreased opioid efficacy or a withdrawal syndrome in patients who had developed physical dependence to buprenorphine. |
Intervention: | If concomitant use is necessary, consider dosage reduction of buprenorphine until stable drug effects are achieved. Monitor patients for respiratory depression and sedation. If a CYP3A4 inhibitor is discontinued, consider increasing the buprenorphine dosage until stable drug effects are achieved. Monitor for signs of opioid withdrawal. |
Examples: | Macrolide antibiotics (e.g., erythromycin), azole-antifungal agents (e.g., ketoconazole), protease inhibitors (e.g., ritonavir) |
CYP3A4 Inducers | |
Clinical Impact: | The concomitant use of buprenorphine and CYP3A4 inducers can decrease the plasma concentration of buprenorphine [see CLINICAL PHARMACOLOGY: Pharmacokinetics ], potentially resulting in decreased efficacy or onset of a withdrawal syndrome in patients who have developed physical dependence to buprenorphine. After stopping a CYP3A4 inducer, as the effects of the inducer decline, the buprenorphine plasma concentration will increase [see CLINICAL PHARMACOLOGY: Pharmacokinetics ], which could increase or prolong both therapeutic effects and adverse reactions and may cause serious respiratory depression. |
Intervention: | If concomitant use is necessary, consider increasing the buprenorphine dosage until stable drug effects are achieved. Monitor for signs of opioid withdrawal. If a CYP3A4 inducer is discontinued, consider buprenorphine dosage reduction and monitor for signs of respiratory depression and sedation. |
Examples: | Rifampin, carbamazepine, phenytoin |
Serotonergic Drugs | |
Clinical Impact: | The concomitant use of opioids with other drugs that affect the serotonergic neurotransmitter system has resulted in serotonin syndrome. |
Intervention: | If concomitant use is warranted, carefully observe the patient, particularly during treatment initiation and dose adjustment. Discontinue buprenorphine if serotonin syndrome is suspected. |
Examples: | Selective serotonin reuptake inhibitors (SSRIs), serotonin and norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), triptans, 5-HT3 receptor antagonists, drugs that affect the serotonin neurotransmitter system (e.g., mirtazapine, trazodone, tramadol), certain muscle relaxants (i.e., cyclobenzaprine, metaxalone), monoamine oxidase (MAO) inhibitors (those intended to treat psychiatric disorders and also others, such as linezolid and intravenous methylene blue). |
Monoamine Oxidase Inhibitors (MAOIs) | |
Clinical Impact: | MAOI interactions with opioids may manifest as serotonin syndrome opioid toxicity (e.g., respiratory depression, coma). |
Intervention: | The use of buprenorphine is not recommended for patients taking MAOIs or within 14 days of stopping such treatment. |
Examples: | phenelzine, tranylcypromine, linezolid |
Mixed Agonist/Antagonist and Partial Agonist Opioid Analgesics | |
Clinical Impact: | May reduce the analgesic effect of buprenorphine and/or precipitate withdrawal symptoms. |
Intervention: | Avoid concomitant use. |
Examples: | butorphanol, nalbuphine, pentazocine |
Muscle Relaxants | |
Clinical Impact: | Buprenorphine may enhance the neuromuscular blocking action of skeletal muscle relaxants and produce an increased degree of respiratory depression. |
Intervention: | Monitor patients for signs of respiratory depression that may be greater than otherwise expected, decrease the dosage of buprenorphine and/or the muscle relaxant as necessary. |
| Examples: | Cyclobenzaprine, metaxalone. |
Diuretics | |
Clinical Impact: | Opioids can reduce the efficacy of diuretics by inducing the release of antidiuretic hormone. |
Intervention: | Monitor patients for signs of diminished diuresis and/or effects on blood pressure and increase the dosage of the diuretic as needed. |
Anticholinergic Drugs | |
Clinical Impact: | The concomitant use of anticholinergic drugs may increase the risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. |
Intervention: | Monitor patients for signs of urinary retention or reduced gastric motility when buprenorphine is used concomitantly with anticholinergic drugs. |
Antiretrovirals: Nucleoside reverse transcriptase inhibitors (NRTIs) | |
Clinical Impact: | Nucleoside reverse transcriptase inhibitors (NRTIs) do not appear to induce or inhibit the P450 enzyme pathway, thus no interactions with buprenorphine are expected. |
| Intervention: | None |
| Antiretrovirals: Non-nucleoside reverse transcriptase inhibitors (NNRTIs ) | |
Clinical Impact: | Non-nucleoside reverse transcriptase inhibitors (NNRTIs) are metabolized principally by CYP3A4. Efavirenz, nevirapine, and etravirine are known CYP3A inducers, whereas delaviridine is a CYP3A inhibitor. Significant pharmacokinetic interactions between NNRTIs (e.g., efavirenz and delavirdine) and buprenorphine have been shown in clinical studies, but these pharmacokinetic interactions did not result in any significant pharmacodynamic effects. |
Intervention: | If prescribing an NNRTI to a patient taking buprenorphine, frequently reevaluate for this interaction and adjust dosing as necessary. |
Examples: | efavirenz, nevirapine, etravirine, delavirdine |
Antiretrovirals: Protease inhibitors (PIs) | |
Clinical Impact: | Studies have shown some antiretroviral protease inhibitors (PIs) with CYP3A4 inhibitory activity (nelfinavir, lopinavir/ritonavir, ritonavir) have little effect on buprenorphine pharmacokinetic and no significant pharmacodynamic effects. Other PIs with CYP3A4 inhibitory activity (atazanavir and atazanavir/ritonavir) resulted in elevated levels of buprenorphine and norbuprenorphine, and patients in one study reported increased sedation. Symptoms of opioid excess have been found in post-marketing reports of patients receiving buprenorphine and atazanavir with and without ritonavir concomitantly. |
Intervention: | Monitor patients taking buprenorphine and atazanavir with and without ritonavir, and dose reduction of buprenorphine may be warranted. |
Examples: | atazanavir, ritonavir |
DESCRIPTION
Buprenorphine hydrochloride is a partial opioid agonist.
The chemical name of buprenorphine hydrochloride is 17-(cyclopropylmethyl)-α-(1,1-dimethylethyl)-4, 5-epoxy-18,19-dihydro-3-hydroxy-6-methoxy-α-methyl-6, 14-ethenomorphinan-7-methanol, hydrochloride [5α, 7α(S)].
Buprenorphine hydrochloride is a white powder, weakly acidic and with limited solubility in water.
Buprenorphine hydrochloride injection is a clear, sterile, injectable agonist-antagonist analgesic intended for intravenous or intramuscular administration. Each ml of Buprenorphine hydrochloride injection contains 0.324 mg buprenorphine hydrochloride (equivalent to 0.3 mg buprenorphine), 50 mg anhydrous dextrose, water for injection and HCl to adjust pH.
Buprenorphine hydrochloride has the molecular formula, C 29 H 41 NO 4 HCl, and the following structure:
Molecular weight: 504.09
CLINICAL PHARMACOLOGY
Mechanism of Action
Buprenorphine is a partial agonist at the mu-opioid receptor and an antagonist at the kappa-opioid receptor. One unusual property of buprenorphine observed in vitro studies is its very slow rate of dissociation from its receptor. This could account for its longer duration of action than morphine, the unpredictability of its reversal by opioid antagonists, and its low level of manifest physical dependence.
Pharmacodynamics
Buprenorphine hydrochloride is a parenteral opioid analgesic with 0.3 mg buprenorphine being approximately equivalent to 10 mg morphine sulfate in analgesic and respiratory depressant effects in adults. Pharmacological effects occur as soon as 15 minutes after intramuscular injection and persist for 6 hours or longer. Peak pharmacologic effects usually are observed at 1 hour. When used intravenously, the times to onset and peak effect are shortened.
Buprenorphine demonstrates narcotic antagonist activity and has been shown to be equipotent with naloxone as an antagonist of morphine in the mouse tail flick test.
Effect s on the Central Nervous System
The principal action of therapeutic value of buprenorphine is analgesia and is thought to be due to buprenorphine binding with high affinity to opioid receptors on neurons in the brain and spinal cord.
Buprenorphine produces respiratory depression by direct action on brain stem respiratory centers. The respiratory depression involves a reduction in the responsiveness of the brain stem respiratory centers to both increases in carbon dioxide tension and electrical stimulation.
Under usual conditions of use in adults, both buprenorphine and morphine show similar dose-related respiratory depressant effects. At adult therapeutic doses, buprenorphine (0.3 mg buprenorphine) can decrease respiratory rate in an equivalent manner to an equianalgesic dose of morphine (10 mg). [see WARNINGS ].
Buprenorphine causes miosis, even in total darkness. Pinpoint pupils are a sign of opioid overdose but are not pathognomonic (e.g., pontine lesions of hemorrhagic or ischemic origins may produce similar findings). Marked mydriasis rather than miosis may be seen due to hypoxia in overdose situations.
Effects on the Gastrointestinal Tract and Other Smooth Muscle
Buprenorphine causes a reduction in motility associated with an increase in smooth muscle tone in the antrum of the stomach and duodenum. Digestion of food in the small intestine is delayed and propulsive contractions are decreased. Propulsive peristaltic waves in the colon are decreased, while tone is increased to the point of spasm, resulting in constipation. Other opioid-induced effects may include a reduction in biliary and pancreatic secretions, spasm of sphincter of Oddi, transient elevations in serum amylase, and opioid-induced esophageal dysfunction (OIED).
Effec ts on the Cardiovascular System
Buprenorphine produces peripheral vasodilation, which may result in orthostatic hypotension or syncope. Manifestations of histamine release and/or peripheral vasodilation may include pruritus, flushing, red eyes, sweating, and/or orthostatic hypotension.
Buprenorphine may cause a decrease or, rarely, an increase in pulse rate and blood pressure in some patients.
Thorough QT studies with buprenorphine products have demonstrated QT prolongation ≤ 15 msec.
Effects on the Endocrine System
Opioids inhibit the secretion of adrenocorticotropic hormone (ACTH), cortisol, and luteinizing hormone (LH) in humans. They also stimulate prolactin, growth hormone (GH) secretion, and pancreatic secretion of insulin and glucagon.
Use of opioids for an extended period of time 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.
Effects on the Immune System
Opioids have been shown to have a variety of effects on components of the immune system in in vitro and animal models. The clinical significance of these findings is unknown. Overall, the effects of opioids appear to be modestly immunosuppressive.
Concentration–Efficacy Relationships
The minimum effective analgesic concentration will vary widely among patients, especially among patients who have been previously treated with opioid agonists. The minimum effective analgesic concentration of buprenorphine for any individual patient may increase over time due to an increase in pain, the development of a new pain syndrome, and/or the development of analgesic tolerance.
Concentration–Adverse Reaction Relationships
There is a relationship between increasing buprenorphine plasma concentration and increasing frequency of dose-related opioid adverse reactions such as nausea, vomiting, CNS effects, and respiratory depression. In opioid-tolerant patients, the situation may be altered by the development of tolerance to opioid-related adverse reactions.
Pharmacokinetics
The limits of sensitivity of available analytical methodology precluded demonstration of bioequivalence between intramuscular and intravenous routes of administration.
Elimination
In postoperative adults, pharmacokinetic studies have shown elimination half-lives ranging from 1.2 to 7.2 hours (mean 2.2 hours) after intravenous administration of 0.3 mg of buprenorphine. A single, ten-patient, pharmacokinetic study of doses of 3 μg/kg in children (age 5 to 7 years) showed a high inter-patient variability, but suggests that the clearance of the drug may be higher in children than in adults. This is supported by at least one repeat-dose study in postoperative pain that showed an optimal inter-dose interval of 4 to 5 hours in pediatric patients as opposed to the recommended 6 to 8 hours in adults.
Metabolism
Buprenorphine undergoes both N-dealkylation to norbuprenorphine and glucuronidation. The N-dealkylation pathway is mediated primarily by CYP3A4. Norbuprenorphine, the major metabolite, can further undergo glucuronidation. Its clearance is related to hepatic blood flow. Studies in patients anesthetized with 0.5% halothane have shown that this anesthetic decreases hepatic blood flow by about 30%.
HOW SUPPLIED
Buprenorphine Hydrochloride Injection
NDC 42023-179-05: 0.3 mg buprenorphine in a 1 mL single dose clear glass vial, supplied in packages of five vials.
Store at 20° to 25°C (68° to 77°F). (See USP Controlled Room Temperature.) Protect from prolonged exposure to light.
The vial stopper is not made with natural rubber latex.
Mechanism of Action
Buprenorphine is a partial agonist at the mu-opioid receptor and an antagonist at the kappa-opioid receptor. One unusual property of buprenorphine observed in vitro studies is its very slow rate of dissociation from its receptor. This could account for its longer duration of action than morphine, the unpredictability of its reversal by opioid antagonists, and its low level of manifest physical dependence.