Buprenorphine
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Buprenorphine
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| Systematic (IUPAC) name | |
| (2S)-2-[(-)-(5R,6R,7R,14S)- 9α-cyclopropylmethyl-4,5-epoxy- 6,14-ethano-3-hydroxy- 6-methoxymorphinan-7-yl]- 3,3-dimethylbutan-2-ol |
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| Identifiers | |
| CAS number | |
| ATC code | N02 N07BC01 |
| PubChem | |
| DrugBank | |
| Chemical data | |
| Formula | C29H41NO4 |
| Mol. mass | 467.64 g/mol |
| Pharmacokinetic data | |
| Bioavailability | 31% (sublingual, from ethanolic solution) ~50-60% (sublingual, high-dose tablet) ~50% (transdermal) |
| Protein binding | 96% |
| Metabolism | hepatic |
| Half life | 20-70, mean 37 hours |
| Excretion | biliary and renal |
| Therapeutic considerations | |
| Pregnancy cat. |
C (USA) |
| Legal status |
Schedule III (USA) |
| Routes | sublingual, IM, IV,transdermal |
Buprenorphine is an opioid drug with partial agonist and antagonist actions. Buprenorphine hydrochloride was first marketed in the 1980s by Reckitt & Colman (now Reckitt Benckiser) as an analgesic, available generally as Temgesic 0.2 mg sublingual tablets, and as Buprenex in a 0.3 mg/ml injectable formulation. In October 2002, the Food and Drug Administration (FDA) of the United States of America additionally approved Suboxone and Subutex, buprenorphine's high-dose sublingual pill preparations for opioid addiction, and as such the drug is now also used for this purpose. In the USA, it has been a Schedule III drug under the United Nations' Convention on Psychotropic Substances[1] since it was rescheduled from Schedule V (the schedule with the lowest restrictions and penalties in the USA) just before FDA approval of Suboxone and Subutex. In the recent years, buprenorphine has been introduced in most European countries as transdermal formulation ("patch") for the treatment of chronic pain.
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[edit] Commercial preparations
British firm Reckitt & Colman (now Reckitt Benckiser) first marketed buprenorphine under the trade names Temgesic (sublingual/parenteral preparations, no active additives) and Buprenex (parenteral, no active additives). Two more recent formulations from Reckitt Benckiser have been approved for opioid addiction treatment in the U.S.: Subutex (white color, bitter, no active additives) and Suboxone (orange color, lemon-lime flavored, one part naloxone for every four parts buprenorphine; hexagon shaped tablet). Subutex is available as 0.4 mg, 2 mg and 8 mg sublingual dosages, Suboxone is marketed in strengths of 2 mg and 8 mg. Suboxone contains opiate agonist as well as the opioid antagonist naloxone to deter illicit intravenous preparation and intranasal use of the tablet The tablets contain 0.5 mg and 2 mg of Naloxon respectively. This is intended to attenuate the effects of buprenorphine on opioid-naive users should this formulation be injected - however no human studies have been done demonstrating the efficacy of this approach with buprenorphine and a growing number of street reports indicate that the naloxone is ineffective. The small presence of naloxone has no clinically significant effect due to the poor absorption via sublingual administration; however, after dosage, very low levels of naloxone may be present within the bloodstream, yet yield no clinical effect; especially due to buprenorphine's extremely high binding affinity--approximately one-half that of buprenorphine.[2]
TIP-40, a US publication dealing with clinical use of Suboxone/Subutex, concede that the naloxone contained in the tablets would not affect someone stabilized on suboxone, even if injected. It mainly serves to deter diversion of the drug, as injecting it is not a viable alternative to injecting other short acting opioids. The naloxone would cause fifteen to forty-five minutes of extreme withdrawal (PWS, precipitated withdrawal syndrome) and even after that, the partial agonist nature of buprenorphine could cause continued withdrawal symptoms. Injecting a crushed tablet in an opioid naive person would cause a high, as the naloxone has nothing to displace in such people, and it is of insufficient binding strength to compete with buprenorphine for receptors.
A solution for injection (usually by the intramuscular route) is marketed for the British veterinary market by Alstoe Animal Health as Vetergesic, licenced for analgesia and sedation in dogs.
Since 2001 buprenorphine is also available transdermally in 35, 52.5 and 70 mcg per hour transdermal patch, that delivers the dose over ninety-six hours. This application form is marketed as Transtec in most European countries by Grunenthal[3] (Napp Pharmaceuticals.in the UK[4] Norpharma in Denmark) for the treatment of moderate to severe cancer pain and severe non-cancer pain not responding to non-opioids. Moreover, a new 5, 10 and 20 mcg per hour patch is marketed as Butrans or Norspan, a once weekly patch for severe chronic pain not responding to non-opioids, marketed by Napp Pharmaceuticals Ltd., and Mundipharma and Grunenthal respectively.
[edit] Pharmacology and pharmacokinetics
Buprenorphine is a thebaine derivative with powerful analgesia approximately twenty-five to forty times as potent as morphine,[5] and its analgesic effect is due to partial agonist activity at μ-opioid receptors, i.e., when the molecule binds to a receptor, it is only partially activated in contrast to a full agonist such as morphine. Buprenorphine also has very high binding affinity for the μ receptor such that opioid receptor antagonists (e.g. naloxone) only partially reverse its effects. These two properties must be carefully considered by the practitioner, as an overdose cannot be easily reversed (although overdose is unlikely in addicted patients or people with tolerance to opioids who use the drug sublingually as meant in the case of Subutex/Suboxone, especially if there are no benzodiazepines involved), and use in persons physically dependent on full-agonist opioids may trigger opioid withdrawal that also cannot be easily reversed and can last over twenty-four hours, as the drug's mean half-life is thirty-seven hours.
Buprenorphine is also a κ-opioid receptor antagonist, and partial/full agonist at the recombinant human ORL1 nociceptin receptor.[6]
Buprenorphine hydrochloride is administered by intramuscular injection, intravenous infusion, via a transdermal patch, or as a sublingual tablet. It is not administered orally, due to very high first-pass metabolism. Buprenorphine is metabolised by the liver, via the CYP3A4 isozyme of the cytochrome P450 enzyme system, into norbuprenorphine (by N-dealkylation) and other metabolites. The metabolites are further conjugated with glucuronic acid and eliminated mainly through excretion into the bile. The elimination half-life of buprenorphine is 20–73 hours (mean 37). Due to the mainly hepatic elimination there is no risk of accumulation in patients with renal impairment and in the elderly.
The main active metabolite, norbuprenorphine, is a δ-opioid receptor and ORL1 receptor agonist, μ- and κ-opioid receptor partial agonist, but buprenorphine antagonizes its effects.[6]
Plasma concentrations after application of transdermal buprenorphine increase steadily and the minimum effective therapeutic dose (100 pg/ml) is reached at eleven hours and twenty-one hours for a single 35 and 70 μg/h patch, respectively. Peak plasma concentration (Cmax) is reached in about sixty hours (305 and 624 pg/ml for the 35 and 70 μg/h strength patch, respectively), and is markedly longer than with 0.3 mg intravenous buprenorphine (0.41 hours). Transdermal buprenorphine has a half-life of approximately thirty hours, and a bioavailability of approximately 50%, which is comparable to sublingual buprenorphine.
[edit] Clinical use
[edit] Indications
[edit] Pain indications
Depending on the application form, buprenorphine is indicated for the treatment of moderate to severe chronic pain or for peri-operative analgesia. For the treatment of chronic pain, the transdermal formulations (not currently available in the U.S. as of January 2008) are nowadays preferred, which can be used both for chronic cancer pain as well as chronic non-malignant pain e.g. musculosceletal and neuropathic pain. The intravenous formulation is mainly used in postoperative pain (e.g. as PCA- patient controlled analgesia) and the sublingual formulation is e.g. used as breakthrough medication for patients with basic transdermal treatment. Advantages of buprenorphine in the treatment of chronic pain are, from a clinical perspective, its relatively long half-life, the option of sublingual and transdermal application and the excellent safety profile (ceiling effect for respiratory depression, lack of immunosuppressive effect, low pharmacokinetic interaction potential, no accumulation in renal impairment).
[edit] Antidepressant features
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A clinical trial conducted at Harvard Medical School in the mid-1990s demonstrated that a majority of unipolar non-psychotic patients with major depression refractory to conventional thymoleptic antidepressants could be successfully treated with buprenorphine.[7] See opioids for other (predominantly favorable) experiments with buprenorphine and other opioids for psychological relief. However, psychological distress is currently not an approved indication for the use of any opioid, and legally it falls in a "grey zone" that is technically legal but a doctor could still face charges regardless (but not for off-label scripting in itself, simply being singled out by the USA's Drug Enforcement Administration (DEA), who prosecute doctors often for using controlled substances for approved uses ("too much")).[8][9] The doctor still needs the proper DEA licensing under the Drug Addiction Treatment Act of 2000 to prescribe Subutex or Suboxone for opioid addiction/dependence.
[edit] Contraindication
Like full agonist opiates, buprenorphine can cause drowsiness, vomiting and respiratory depression. Taking buprenorphine in conjunction with central nervous system (CNS) depressants such as sedatives, tranquilizers, alcohol, and especially benzodiazepines can be particularly dangerous.[10] Falling asleep while abusing this drug, especially while combining it with other central nervous system depressants, can be extremely dangerous and thus greatly increases the chance of serious complications or death.
[edit] Adverse effects
Common adverse drug reactions associated with the use of buprenorphine are similar to those of other opioids and include: nausea and vomiting, drowsiness, dizziness, headache, itch, dry mouth, miosis, orthostatic hypotension, male ejaculatory difficulty, decreased libido, urinary retention. Constipation and CNS effects are seen less frequently than with e.g. morphine[11] Hepatic necrosis and hepatitis with jaundice have been reported with the use of buprenorphine, especially after intravenous injection of crushed tablets.
The most severe and serious adverse reaction associated with opioid use in general is respiratory depression, the mechanism behind fatal overdose. Buprenorphine behaves differently than other opioids in this respect, as it shows a ceiling effect for respiratory depression.[11]Moreover, former doubts on the antagonisation of the respiratory effects by Naloxone have been disproved: Buprenorphine effects can be antogonised with a continuous infusion of Naloxone.[12] Of course, concurrent use of buprenorphine and CNS depressants (such as alcohol or benzodiazepines) is contraindicated as it may lead to fatal respiratory depression.
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In people on medium- to long-term maintenance with Suboxone or Subutex do not have a major risk of overdose, as long as the drug is used properly (as prescribed), and benzodiazepines are not prescribed to individuals without a tolerance to opioids.
As with other opioids, dependence and tolerance may occur but are generally manageable when used properly. There is little evidence that buprenorphine is less likely to cause such problems. Maintenance dosages can remain at the same moderate level indefinitely, and in many cases even lowered, without discomfort. Due to buprenorphine's pharmacological actions, raising the dosage will not result in a stronger analgesic effect after a certain point (around 16–32 mg), beyond which the drug will actually have a reduced analgesic effect.
The partial agonist activity of buprenorphine combined with its high affinity for μ-opioid receptor means that it may act clinically as an antagonist and thus precipitate opioid withdrawal symptoms when an opioid-dependent patient is commenced on the drug soon after the use of another opioid drug. Patients are advised to wait between twenty-four and thirty-six hours after their last use of short-acting opioids (such as heroin or oxycodone) before beginning treatment with buprenorphine. Those using long-acting opioids, such as methadone, should only commence treatment once withdrawal symptoms are present. Beginning any earlier may result in extreme cases of opioid withdrawal. Additionally, it is recommended that the patient be on no more than 30 mg of methadone per day when switching to buprenorphine.
[edit] Dependence treatment
Buprenorphine sublingual preparations are often used in the management of opioid dependence (that is, dependence on heroin, oxycodone, hydrocodone, morphine, oxymorphone, fentanyl or other opioids). The Suboxone and Subutex preparations were approved for this indication by the United States FDA in October 2002. This was only possible due to the Drug Addiction Treatment Act of 2000 that for the first time since 1914-1920 (conflicting Supreme Court rulings - rulings that would not stand to today's Supreme Court as they ruled that maintenance or detox treatment is not medical treatment, and likely was not what was intended by Congress) made it legal for doctors to prescribe opioids themselves to manage addiction ("maintenance") or for short-term detox (special doctors in registered clinics are excluded from these blanket restrictions). This law is limited to Schedules III through V only - thus excluding methadone and stronger opioids.
The use of Medication assisted treatment in the management of opioid dependence is highly regulated, owing to the sometimes controversial nature of this aspect of harm reduction policy. In the United States, a special federal waiver is required to prescribe Subutex and Suboxone for opioid addiction treatment on an outpatient basis. However, if the doctor meets none of the other clarifications, an eight-hour course is all that is required). Each approved prescriber is allowed to manage only thirty patients on buprenorphine for opioid addiction as outpatients;[13] the U.S. Senate has passed a bill relaxing this restriction for group practices only as of May 25, 2006[citation needed]. Physicians are only required to have had their original waiver for one year. No clinical experience is required to request an additional exemption within DATA 2000 allowing a one hundred patient limit effective as of 12/29/2006 (public law 109-469).[citation needed] Similar restrictions are placed on prescribers in many other jurisdictions. Buprenorphine is heavily regulated in Australia relatively, and while the number of patients isn't limited generally daily visits for supervised dosing at a pharmacy is required, such as methadone, and methadone where used is used in lower relative doses.[citation needed] On September 21, 2006, actor and comedian Artie Lange revealed on The Howard Stern Show that he had overcome heroin addiction the previous year. He said buprenorphine was essential to countering the effects of opioid withdrawal and described it as a 'miracle pill'. The withdrawal from Buprenorphine is quite similar to that of other opioids, but like methadone, it has a long half life, causing a longer, but milder withdrawal.
[edit] Buprenorphine versus Methadone
Buprenorphine and methadone are medications used for detoxification, short- and long-term maintenance treatment. Each agent has its relative advantages and disadvantages.
In terms of efficacy (i.e. treatment retention, negative urine samples), high-dose buprenorphine (such as that commonly found with Subutex/Suboxone treatment; 8-16 mg typically) has been found to be superior to 20-40 mg of methadone per day (low dose) and equatable anywhere between 50-70 mg (moderate dose),[14] to up to 100 mg (high dose)[15] of methadone a day. (Methadone, however, can continue to increase in effectiveness over 100 mg (although it is a debatable topic methadone has been used in doses up to 1,000 mg per day) but this would constitute "very high dose" (the term "very high dose" quoted in those studies has little meaning in the real world of methadone maintenance clinics as it is routine practice to put new patients on doses of at least 80 mg to achieve the so-called blockade effect preventing patients from getting "high" from other opiates) in this measurement commonly used by studies, including those quoted. In all cases, high-dose buprenorphine has been found to be far superior to placebo and an effective treatment for opioid addiction, with retention rates of 50% as a minimum.[14][15][16][17] It is also worth noting that while methadone's effectiveness is generally thought to increase with dose, buprenorphine has a ceiling effect at 32 mg[18][19] That is, while a methadone dose of 80 mg will likely be more effective than a methadone dose of 60 mg, (see Methadone#Dosage) a buprenorphine dose of 40 mg will not be more effective than a buprenorphine dose of 32 mg.
Buprenorphine sublingual tablets (Suboxone and Subutex for opioid addiction) have a long duration of action which may allow for dosing every two or three days, as tolerated by the patient, compared with the daily dosing (some patients receive twice daily dosing) required to prevent withdrawals with methadone. Once one has been taking a maintenance dose of methadone for some time, withdrawal effects do not begin in earnest until two to three days after the last dose taken. However, buprenorphine is generally taken by maintenance therapy patients daily. In the United States, following initial management, a patient is typically prescribed up to a one month supply for self-administration. It is often misunderstood that the patient has to receive other therapy in this situation, but the law simply states that the prescribing physician needs to be capable of referring the patient to other addiction treatment (i.e. psychotherapy or support groups,) and many (but not all) physicians are aware of this and simply recommend therapy, or as they deem fit have therapy required.
Buprenorphine may be more convenient for some users because patients can be given a thirty day take home dose relatively soon after starting treatment, hence making treatment more convenient relative to those who need to visit a methadone dispensing facility daily to receive their methadone. The facilities, which are regulated at the state and federal level, initially are only permitted to allow patients to receive take home doses (to be self-administered at the appropriate time) on a day when the clinic is regularly closed or on a pre-scheduled holiday. It is only a minimum of three months of compliance (i.e., proven sobriety, demonstration of being able to safely store the medication) that patients are permitted regularly scheduled take home doses aside from the possible exceptions for weekends and holidays. Ultimately, American patients on methadone maintenance therapy are permitted a maximum of a one month supply of take home medication, much more than most buprenorphine patients get, and this is only permitted after a minimum of two years compliance. In Florida, patients cannot receive a month supply until five years of compliance.[20] Most buprenorphine patients are not prescribed more than one month's worth of buprenorphine at a time. However, buprenorphine patients, as a rule, are able to get their one month supply much earlier in their use of the drug than methadone patients.
Therefore, some would argue that buprenorphine as a maintenance treatment offers a clear advantage over methadone. This is only a clear advantage in terms of convenience as the daily dosing schedule required by methadone clinics is more effective in making sure that the patient is maintaining sobriety as a nurse administers the methadone only if the patient appears lucid and sober and does not smell of alcohol or marijuana; additionally the daily dosing schedule helps keeps patients on a healthy track to sobriety as they are required to wake up early to receive their dose before work. Buprenorphine patients are more generally not required to make daily office visits and are often very quickly permitted to obtain a one month prescription for the medication. However, methadone patients in states that don't impose additional strictures (additional to the United States federal limit of a one month supply) on the amount of take-home doses available have a convenience factor similar to that which buprenorphine patients enjoy with their standard one month supply, after a waiting period of at least two years. However, this is not the case in states with excessive regulation. For that reason, there are also many professionals who are advocating for office-based methadone treatment, like office-based buprenorphine treatment, in the United States and elsewhere. Such treatment with full opiate agonists is already available on a limited basis in the UK, and has been ever since heroin was made illegal, with an interruption of a few decades which occurred, likely under pressure from the United States,[citation needed] during the worldwide escalation of the War on Drugs which occurred during the 1960's and 1970's. In fact, in the UK a doctor may prescribe any opiate to a person, regardless of their complaint. In practice, methadone is most often used, although morphine and heroin are also less frequently prescribed on a maintenance basis. The UK has a smaller number of opiate users, per capita, than the United States,[citation needed] which many attribute to the availability of full opiate agonist prescriptions to users, which reduces the amount of opiates sold illicitly and, in turn, the number of users of other drugs who encounter and begin using the opiates. Therefore, it could be argued that buprenorphine may not be as attractive a treatment option in the UK due to full opiate agonists such as heroin maintenance being an option for a small amount of addict seeking treatment. (see Heroin#Heroin prescription)
Buprenorphine may and is generally viewed to have a lower dependence-liability than methadone. In other words, withdrawal from buprenorphine is less difficult. Like methadone treatment, buprenorphine treatment can last anywhere from several days (for detoxification purposes) to eighteen months if patient and doctor both feel that is the best course of action. Additionally, the opinion of those in the medication assisted treatment field is generally shifting to longer-term treatment periods, which may last indefinitely, due to the anti-depressant effects opioids seem to have on some patients, as well as the high relapse potential among those patients discontinuing maintenance therapy. The choice of buprenorphine versus methadone in the mentioned situation (by the patient) is usually due to the benefits of the less-restrictive outpatient treatment; prescriptions for take-home doses for up to a month early versus the possibility of heavy restrictions in some states and frequent visits to the clinic and the possibility of the "stigma" of going to a methadone clinic as compared to making trips to a doctor's office. Buprenorphine is also significantly more expensive than methadone and this seems to add to its better reputation. Also, in some states, there is a long waiting list for admission to a methadone maintenance program versus those with the money to afford seeing an addiction specialist each month in addition to the cost of medication.
The sometimes less-severe withdrawal effects may make it easier for some patients to discontinue use as compared with methadone, which is generally thought to be associated with a more severe and prolonger withdrawal. However, no evidence thus far exists that sustaining abstinence post-buprenorphine maintenance is any more likely than post-methadone maintenance.
Another issue of concern for patients considering beginning any maintenance therapy or switching from one maintenance therapy to another is the transition associated with this switch. Due to buprenorphine's high-affinity to opioid receptors in the brain, care needs to be taken when a patient is transitioning from one drug (i.e., heroin) or medication (i.e., methadone) to buprenorphine. Essentially, if an opioid-dependent patient is not in sufficient withdrawal, introduction of buprenorphine may precipitate withdrawal. In layman's terms, in a sufficient dose, buprenorphine "pushes" any other opioids off of the receptors, but is itself not always "strong enough" to counteract the withdrawal symptoms this causes.[21] Thus, opioid-dependent patients, particularly those on methadone or another long-acting medication or drug should be thoroughly honest with their prescribing doctor about their drug use, particularly in the days immediately preceding their induction onto buprenorphine, whether for detoxification or maintenance. In contrast, the transition from buprenorphine or other opioids to methadone is generally easier, and any discomfort or side effects are more likely to be easily remedied with dose adjustments.
Buprenorphine, as a partial μ-opioid receptor agonist, has been claimed and is generally viewed to have a less euphoric effect compared to the full agonist methadone, and was therefore predicted less likely to be diverted to the black market (as reflected by its C–III status versus methadone's more restrictive C–II status in the USA), as well as that buprenorphine is generally accepted as having less potential for abuse than methadone. It is also worth noting that neither methadone nor buprenorphine are to cause euphoria when taken long-term at the appropriate dose. However, in at least one study in which opiate users who were currently not using were given buprenorphine, several other opioids, and placebo intramuscularly, subjects identified the drug they were injected with as heroin when it was actually buprenorphine.[22] This evidence tends to support the contentions of those who reject the notion that buprenorphine, when injected, is only marginally euphoric, or significantly less euphoric than other opiates.
It should be noted that, in an effort to prevent injection of the drug, the Suboxone formulation includes naloxone in addition to the buprenorphine. When naloxone is injected, it is supposed to precipitate opiate withdrawal and blocks the effects of any opiate. However, contrary to popular belief, since buprenorphine has such a high affinity (higher then naloxone), the naloxone does not affect the user even when injected.[citation needed] The naloxone does not precipitate withdrawal or block the effect of the buprenorphine when taken sublingually. The Subutex formulation does not include naloxone, and therefore has a higher potential for injection abuse. However, Subutex is prescribed significantly less than Suboxone for just this reason. Methadone, on the other hand, is typically given to patients at clinics in a liquid solution, to which water is generally added. This makes injection difficult without evaporating the liquid and taking other measures. Therefore, injection of buprenorphine as found in the preparations provided to opiate users simpler than injection of methadone, although data on the relative incidence is not currently available. Additionally, in the US, buprenorphine is found far less often on the black market as compared to methadone. It is also worth noting that most methadone found on the black market is medication diverted from pain patients, not from methadone maintenance patients. Although methadone is generally not a drug of choice for opioid addicts due to its long-acting nature and relatively little euphoria associated with its use, especially when compared to other drugs of abuse such as heroin and Percocet, it is used by addicts to relieve withdrawal symptoms when their opiate of choice cannot be obtained. Most methadone bought from the black market is thought to be bought by already opioid-dependent persons attempting to circumvent the substance abuse treatment system and detoxify themselves with the methadone or simply by people who wish to use the drug recreationally, just as other opiates are used. The vast majority of the methadone diverted to the black market is not diverted from methadone clinics for opioid dependent persons, but rather it is diverted by a minority of the people who receive prescription for methadone for pain.
[edit] Blockade effect
The Suboxone preparation contains the μ-opioid receptor antagonist naloxone which is intended only to prevent abuse (i.e. injection) of the buprenorphine, not, as is commonly misunderstood, to block the effects of other opiates. Buprenorphine itself is mixed agonist/antagonist, and, as such, buprenorphine blocks the activity of other opiates and induces withdrawal in opiate dependent individuals who are currently physically dependent on another opiate. This is why users must wait until they are in withdrawal before beginning treatment with buprenorphine.
Buprenorphine itself binds more strongly to receptors in the brain than do other opioids, making it more difficult to become intoxicated via other opioids when buprenorphine is in the system, regardless of the presence of the naloxone. (Small, but measurable, amounts of naloxone can be absorbed and detected via the sublingual route, and while this is insignificant and has no subjective effect, there are anecdotal reports of hypersensitivity to naloxone in rare cases. These reports are not fully substantiated.) If enough buprenorphine is in the system, however, it has the same type of effect as naloxone, i.e. it completely or nearly completely blocks or reverses opiate effects from other opioids. 0.3 mg of buprenorphine parenterally is equivalent in antagonistic effect to between 0.4 and 2.0 mg of naloxone parenterally, but with a much longer half-life. Methadone also blocks the effects of other opioids, and at commonly used methadone maintenance doses, the degree of blockade is similar. Unlike buprenorphine, however, this is not due to any opiate antagonist-like action of methadone. Instead, daily use of methadone, like daily use of any of the opiate agonists, results in tolerance to all opiates, called "cross-tolerance". However, it is still possible to use other opioids on either treatment regime, although many people find "getting high" to be difficult or unattainable.
Switching to buprenorphine from methadone is often difficult and withdrawals lasting several days or more are often encountered mostly when the methadone dose is any higher than 30 mg/day (the suggested and usual dose for switching to buprenorphine). A 30 mg dose of methadone is relatively low, and some patients have difficulty reaching that dose, for a variety of reasons.[citation needed] Healthy users of methadone who commit to a slow taper, however, frequently find success in tapering to 30 mg in order to switch to buprenorphine, as well as in tapering off of methadone completely without the use of buprenorphine. Switching to buprenorphine at higher doses of methadone may be uncomfortable for the user. One reason is that users must be in withdrawal before switching to buprenorphine, and users of opiates with long half-lives, like methadone, may need to wait several days after their last dose of methadone before they are fully in withdrawal and ready to begin buprenorphine. User of heroin, hydrocodone, oxycodone, and morphine, as well as most other common opiates, only need to wait a maximum of twenty-four hours before they are fully in withdrawal and ready to begin buprenorphine. For this reason, some doctors switch methadone users to a shorter acting opiate, such as morphine, for a few days before allowing withdrawal to occur and beginning buprenorphine. Unfortunately, due to the unique qualities of both methadone and buprenorphine, switching to and using buprenorphine during pregnancy instead of methadone is unlikely to be helpful, since the strain of withdrawal on the body is far more dangerous for a fetus than the use of an opiate such as methadone -- about which the data suggests that after the first few weeks of life, no developmental differences are found between children born to mothers who were stable on an opiate during pregnancy versus those who were not taking any opiates during pregnancy. This stands in stark contrast to the results of using the otherwise socially acceptable drug alcohol during pregnancy. Also, data regarding buprenorphine's safety during pregnancy is less available than data on methadone during pregnancy -- data which has established the safety of methadone during pregnancy and the lack of lasting effects on children of mothers on methadone during pregnancy. On the other hand, switching from buprenorphine to methadone is relatively easy as methadone is a full opiate agonist which does not have a ceiling, and can stop the withdrawal symptoms of users at any dosage of other opiates, including buprenorphine.
[edit] Inpatient rehabilitation
The practice of using buprenorphine (Subutex or Suboxone) in an inpatient rehabilitation setting is increasing rapidly,[citation needed] whereas methadone-based detox is the standard. It is also being used in social model treatment settings. These rehabilitation programs consist of "detox" and "treatment" phases. The detoxification ("detox") phase consists of medically-supervised withdrawal from the drug of dependency on to buprenorphine, sometimes aided by the use of medications such as benzodiazepines like oxazepam or diazepam (modern milder tranquilizers that assist with anxiety, sleep, and muscle relaxation), clonidine (a blood-pressure medication that may reduce some opioid withdrawal symptoms), and anti-inflammatory/pain relief drugs such as ibuprofen. Switching to buprenorphine from a short-acting drug including Heroin, morphine, fentanyl, hydromorphone and hydrocodone (Vicodin), or oxycodone (Oxycontin and Percocet) is not too difficult for most people, and as long as the patient waited until they were in full withdrawals or longer before starting the buprenorphine medication, little further acute symptoms are an issue; The patient needs to be stabilized on a proper dose and monitored regardless. Switching from methadone is much more difficult, and with all cases if the patient takes buprenorphine prematurely (before full withdrawal symptoms) it can precipitate worse withdrawals than would have been had if the person had waited properly, and they can be long-lasting.
The treatment phase begins once the patient is stabilized and receives medical clearance. This portion of treatment comprises multiple therapy sessions, which include both group and individual counseling with various chemical dependency counselors, psychologists, psychiatrists, social workers, and other professionals. Additionally, many treatment centers utilize 12-step facilitation techniques, embracing the 12-step programs practiced by such organizations as Alcoholics Anonymous and Narcotics Anonymous. Some on maintenance therapies have veered away from such organizations as Narcotics Anonymous, instead opting to create their own 12-step fellowships (such as Methadone Anonymous [7]) or depart entirely from the 12-step model of recovery (using a program such as SMART Recovery [8]).
Patients who enter rehabilitation voluntarily (as opposed to those who are court-ordered) can often choose a facility with the option of only staying for detox. Alternatively they can enter treatment facilities that provide the option to complete both detox and longer-term treatment. Completing both increases the probability of success.[citation needed] Abstinence alone has a very low efficacy in rehabilitating patients. In contrast, buprenorphine maintenance has a high efficacy.[15][14] Most rehabilitation programs do not have or do not allow scientific studies to be conducted to contrast to abstinence alone and buprenorphine or methadone maintenance, including Narcotics Anonymous. NA's twelve traditions and overriding principle of anonymity would make such research potentially contentious and internally problematic.[citation needed] Whilst the maintenance / abstinence debate is a hot topic and strong arguments in support of both Narcotics Anonymous and buprenorphine maintenance have been made, individuals tend to gravitate the alternative that works best for them. Furthermore, the two approaches need not necessarily be mutually exclusive. Rehabilitation programs typically average about thirty days for primary care, but some may extend anywhere from ninety days to six months in an extended care unit. It is considered essential by the programs that administer them that patients in abstinence-based treatment form networks with other addiction survivors and engage in mutual-help groups, aftercare and other related activities after treatment in order to improve their chances of achieving long-term abstinence from opioids. Statistically, long-term abstinence is not widely prevalent.
Buprenorphine is sometimes used only during the detox protocol with the purpose of reducing the patient's use of mood-altering substances. It considerably reduces acute opioid withdrawal symptoms that are normally experienced by opioid-dependent patients on cessation of those opioids, including diarrhea, vomiting, fever, chills, cold sweats, muscle and bone aches, muscle cramps and spasms, restless legs, agitation, gooseflesh, insomnia, nausea, watery eyes, runny nose and post-nasal drip, nightmares, etc. The buprenorphine detox protocol usually lasts about seven to ten days, provided that the patient does not need to be detoxed from any additional addictive substances, as previously mentioned.
During this time, Suboxone or Subutex will be administered or the patient will be monitored taking the medication. Generally, the patient takes a single dose each day (a single dose may keep the patient comfortable for up to forty-eight to seventy-two hours, but medical professionals in many treatment facilities prescribe one or more than one dose every twenty-four hours to ensure that a consistent, active level of the medication remains in the patient's central nervous system, a key element of maintenance; also the level of dosage is usually around the previously described plateau, after which there is no noticeable increase in the effects of the drug. Typically, the first day dosage is no more than 8 mg or it may precipitate withdrawals as antagonistic effects overwhelm agonistic effects, after which initial daily dose totals around 8-16 mg of either Suboxone or Subutex. The dosage is slowly tapered each day and the medication is usually stopped thirty-six to forty-eight hours prior to the end of the detox program, with the patient's vitals monitored up until discharge from the detox program.
During the detox period of any situation, despite the evidence that suggests that the naloxone in Suboxone has no clinically significant effect, except for anecdotal reports of hypersensitivity in (if proven) rare cases, Subutex is urged over Suboxone by the manufacturer and users are likely to receive it during the first few days.
[edit] References
- ^ List of psychotropic Substances under international control
- ^ NIDA study
- ^ Transtec Summary of Product Characteristics
- ^ Napp Pharmaceuticals
- ^ http://coretext.org/show_detail.asp?recno=6481 Reckitt Benckiser Buprenorphine Bibliography
- ^ a b Huang P. et al. (2001): "Comparison of pharmacological activities of buprenorphine and norbuprenorphine: norbuprenorphine is a potent opioid agonist", J. Pharmacol. Exp. Ther. 297(2):688-95. PMID 11303059
- ^ Bodkin JA. et al. (1995): "Buprenorphine treatment of refractory depression", Journal of Clinical Psychopharmacology 15:49-57. PMID 7714228
- ^ [1]
- ^ [2]
- ^ Suboxone FAQ
- ^ a b Budd K, Raffa RB. (edts.) Buprenorphine - The unique opioid analgesic. Thieme 2005 (ISBN 3-13-1342211-0)
- ^ Van Dorp E. et al. (2006) Naloxone reversal of buprenorphine- induced respiratory depression. Anesthesiology 105 (1): 51-57
- ^ naabt.org
- ^ a b c R. S. Schottenfeld et. al (1997) Department of Psychiatry, Yale University School of Medicine
- ^ a b c Rolley Johnson et al., NEJM, 343(18):1290-1297, 2000
- ^ Strain et al. (1998)
- ^ Ling et al. (1998).
- ^ [3]
- ^ [4].
- ^ [5]
- ^ [6]
- ^ Buprenorphine and reward
[edit] External links
- SAMHSA, federal U.S. buprenorphine program for opioid addiction
- Government-run physician locator, listing of U.S. doctors who can prescribe buprenorphine for opioid addiction
- Non-government physician locator, another listing of U.S. doctors who can prescribe buprenorphine for opioid addiction
- National Alliance of Advocates for Buprenorphine Treatment, NAABT.org, non-profit educational site
- Australian National Buprenorphine Policy
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