|Summary sheet: Methadone|
|Common names||Methadone, Dolophine|
|Routes of Administration|
|Selective serotonin re-uptake inhibitors|
|Serotonin-norepinephrine reuptake inhibitors|
Methadone (sold under trade names such as Dolophine and Methadose) is a synthetic opioid analgesic used for the treatment of moderate to severe pain and for the treatment of opioid addiction. It is commonly used to treat and manage the symptoms of opioid addiction. The subjective effects are similar to those of other synthetic opioids such as fentanyl, however, most users note a significantly stronger euphoria. Like dextropropoxyphene, the use of methadone is associated with cardiac arrhythmia, however it is more common with dextropropoxyphene than it is with methadone.
- 1 Chemistry
- 2 Pharmacology
- 3 Subjective effects
- 4 Toxicity and harm potential
- 5 Legal issues
- 6 See also
- 7 External links
- 8 References
Methadone is an opioid of the diphenylpropylamine class, featuring two phenyl rings attached to carbon R4 of the main 2-oxo-6-dimethylaminoheptane chain. It exists as a racemic mixture of both dextromethadone and levomethadone. It is also similar in structure to tapentadol and dextropropoxyphene.
Opioids exert their effects by binding to and activating the μ-opioid receptor. This occurs because opioids structurally mimic endogenous endorphins which are naturally found within the body and also work upon the μ-opioid receptor set. The way in which opioids structurally mimic these natural endorphins results in their euphoria, pain relief and anxiolytic effects. This is because endorphins are responsible for reducing pain, causing sleepiness, and feelings of pleasure. They can be released in response to pain, strenuous exercise, orgasm, or general excitement. The bioavailability of orally administered methadone can vary from 40% to around 99%. Methadone is metabolized by the cytochrome P450 system.
Unlike most opioids, methadone is a weak serotonin reuptake inhibitor as well as a weak NMDA antagonist. Similarly to dextropropoxyphene, methadone is a nicotinic acetylcholine receptor antagonist.
Binding affinities (Ki)
- Mu opioid agonist - 24.8 nM
- Kappa opioid agonist - 543 nM
- Delta opioid agonist - 1674 nM
Disclaimer: The effects listed below are cited from the Subjective Effect Index (SEI), which relies on assorted anecdotal reports and the personal experiences of PsychonautWiki contributors. As a result, they should be taken with a healthy amount of skepticism. It is worth noting that these effects will not necessarily occur in a consistent or reliable manner, although higher doses (common+) are more likely to induce the full spectrum of reported effects. Likewise, adverse effects become much more likely on higher doses and may include serious injury or death.
The general sensation of methadone can be described as one of euphoria, relaxation, anxiety suppression and pain relief.
- Pain relief
- Physical euphoria - This particular substance can be considered as less intense in its physical euphoria when compared with that of morphine or diacetylmorphine (heroin), but stronger than that of other synthetic opioids such as tramadol. The sensation itself can be described as extreme feelings of intense physical comfort, warmth, love and bliss.
- Respiratory depression - At low to moderate doses, this effect results in the sensation that the breath is slowed down mildly to moderately, but does not cause noticeable impairment. At high doses and overdoses, opioid-induced respiratory depression can result in a shortness of breath, abnormal breathing patterns, semi-consciousness, or unconsciousness. Severe overdoses can result in a coma or death without immediate medical attention.
- Cough suppression
- Difficulty urinating
- Pupil constriction
- Decreased libido
- Appetite suppression
- Orgasm suppression
- Cognitive euphoria - This particular substance can be considered as less intense in its cognitive euphoria when compared with that of morphine or diacetylmorphine (heroin), but stronger than that of other synthetic opioids such as tramadol. The sensation itself can be described as powerful and overwhelming feeling of emotional bliss, contentment, and happiness.
- Anxiety suppression
- Compulsive redosing
- Dream potentiation
There are currently no anecdotal reports which describe the effects of this compound within our experience index. Additional experience reports can be found here:
Toxicity and harm potential
Methadone has a moderate toxicity relative to dose. As with all opioids, long-term effects can vary but can include diminished libido, apathy and memory loss. It is also potentially lethal when mixed with depressants like alcohol or benzodiazepines and generally has a wider range of substances which it is dangerous to combine with in comparison to other opioids. Methadone is known to lower the seizure threshold. It should not be taken during benzodiazepine withdrawals as this can potentially cause seizures.
It is strongly recommended that one use harm reduction practices when using this drug.
Tolerance and addiction potential
As with other opioids, the chronic use of methadone can be considered extremely addictive with a high potential for abuse and is capable of causing psychological dependence among certain users. When addiction has developed, cravings and withdrawal symptoms may occur if a person suddenly stops their usage.
Tolerance to many of the effects of methadone develops with prolonged and repeated use. The rate at which this occurs develops at different rates for different effects, with tolerance to the constipation-inducing effects developing particularly slowly for instance. This results in users having to administer increasingly large doses to achieve the same effects. After that, it takes about 3 - 7 days for the tolerance to be reduced to half and 1 - 2 weeks to be back at baseline (in the absence of further consumption). Methadone presents cross-tolerance with all other opioids, meaning that after the consumption of methadone all opioids will have a reduced effect.
The risk of fatal opioid overdoses rise sharply after a period of cessation and relapse, largely because of reduced tolerance. To account for this lack of tolerance, it is safer to only dose a fraction of one's usual dosage if relapsing. It has also been found that the environment one is in can play a role in opioid tolerance. In one scientific study, rats with the same history of heroin administration were significantly more likely to die after receiving their dose in an environment not associated with the drug in contrast to a familiar environment.
Although many psychoactive substances are reasonably safe to use on their own, they can quickly become dangerous or even life-threatening when combined with other substances. The list below includes some known dangerous combinations (although it cannot be guaranteed to include all of them). Independent research (e.g. Google, DuckDuckGo) should always be conducted to ensure that a combination of two or more substances is safe to consume. Some interactions listed have been sourced from TripSit.
- Alcohol - Both substances potentiate the ataxia and sedation caused by the other and can lead to unexpected loss of consciousness at high doses. Place affected patients in the recovery position to prevent vomit aspiration from excess. Memory blackouts are likely
- Amphetamines - Stimulants increase respiration rate which allows for a higher dose of opiates than would otherwise be used. If the stimulant wears off first then the opiate may overcome the user and cause respiratory arrest.
- Benzodiazepines - Central nervous system and/or respiratory-depressant effects may be additively or synergistically present. The two substances potentiate each other strongly and unpredictably, very rapidly leading to unconsciousness. While unconscious, vomit aspiration is a risk if not placed in the recovery position blackouts/memory loss likely.
- Cocaine - Stimulants increase respiration rate, which allows for a higher dose of opiates than would otherwise be used. If the stimulant wears off first then the opiate may overcome the patient and cause respiratory arrest.
- DXM - Generally considered to be toxic. CNS depression, difficulty breathing, heart issues, and liver toxicity have been observed. Additionally if one takes DXM, their tolerance of opiates goes down slightly, thus causing additional synergistic effects.
- GHB/GBL - The two substances potentiate each other strongly and unpredictably, very rapidly leading to unconsciousness. While unconscious, vomit aspiration is a risk if not placed in the recovery position
- Ketamine - Both substances bring a risk of vomiting and unconsciousness. If the user falls unconscious while under the influence there is a severe risk of vomit aspiration if they are not placed in the recovery position.
- MAOIs - Coadministration of monoamine oxidase inhibitors (MAOIs) with certain opioids has been associated with rare reports of severe adverse reactions. There appear to be two types of interaction, an excitatory and a depressive one. Symptoms of the excitatory reaction may include agitation, headache, diaphoresis, hyperpyrexia, flushing, shivering, myoclonus, rigidity, tremor, diarrhea, hypertension, tachycardia, seizures, and coma. Death has occurred in some cases.
- MXE - MXE can potentiate the effects of opioids but also increases the risk of respiratory depression and organ toxicity.
- Nitrous - Both substances potentiate the ataxia and sedation caused by the other and can lead to unexpected loss of consciousness at high doses. While unconscious, vomit aspiration is a risk if not placed in the recovery position. Memory blackouts are common.
- PCP - PCP may reduce opioid tolerance, increasing the risk of overdose.
- Tramadol - Increased risk of seizures. Tramadol itself is known to induce seizures and it may have additive effects on seizure threshold with other opioids. Central nervous system- and/or respiratory-depressant effects may be additively or synergistically present
- Grapefruit - While grapefruit is not psychoactive, it may affect the metabolism of certain opioids. Tramadol, oxycodone, and fentanyl are all primarily metabolized by the enzyme CYP3A4, which is potently inhibited by grapefruit juice. This may cause the drug to take longer to clear from the body. it may increase toxicity with repeated doses. Methadone may also be affected. Codeine and hydrocodone are metabolized by CYP2D6. People who are on medicines that inhibit CYP2D6, or that lack the enzyme due to a genetic mutation will not respond to codeine as it can not be metabolized into its active product: morphine.
- Psychedelics - Methadone is known to lower the seizure threshold and psychedelics may act as triggers for seizures in those who are susceptible to them.
Serotonin syndrome risk
While methadone has been reported to occasionally cause serotonin syndrome when combined with certain substances (such as those listed below), anecdotal reports suggests that it does so at a much lower rate than tramadol. Combinations with the following substances can cause dangerously high serotonin levels. Serotonin syndrome requires immediate medical attention and can be fatal if left untreated.
- MAOIs such as syrian rue, banisteriopsis caapi, 2C-T-7, αMT, phenelzine, selegiline, and moclobemide
- Serotonin releasers such as MDMA, 4-FA, methamphetamine, methylone and αMT
- Selective serotonin re-uptake inhibitors (SSRIs)
- Serotonin-norepinephrine reuptake inhibitors (SNRIs) such as tramadol and DXM
This legality section is a stub.
As such, it may contain incomplete or wrong information. You can help by expanding it.
- Canada: Methadone is a Schedule I Controlled Substance.
- Germany: Methadone is a controlled substance under Anlage III of the BtMG. It can only be prescribed on a narcotic prescription form.
- Russia: Methadone is a Schedule I controlled substance.
- United Kingdom: Methadone is a Class A, Schedule 2 drug in the United Kingdom.
- United States: Methadone is a Schedule II Controlled Substance.
- Risks of Combining Depressants (Tripsit) | https://tripsit.me/combining-depressants/
- Blockade of Rat α3β4 Nicotinic Receptor Function by Methadone, Its Metabolites, and Structural Analogs | http://jpet.aspetjournals.org/content/299/1/366.long
- Affinities of Dihydrocodeine and its Metabolites to Opioid Receptors - Helmut Schmidt et al. (August 2002) | http://onlinelibrary.wiley.com/doi/10.1034/j.1600-0773.2002.910203.x/full
- Why Heroin Relapse Often Ends In Death - Lauren F Friedman (Business Insider) | http://www.businessinsider.com.au/philip-seymour-hoffman-overdose-2014-2
- Siegel, S., Hinson, R., Krank, M., & McCully, J. (1982). Heroin “overdose” death: contribution of drug-associated environmental cues. Science, 216(4544), 436–437. https://doi.org/10.1126/science.7200260
- Gillman, P. K. (2005). Monoamine oxidase inhibitors, opioid analgesics and serotonin toxicity. British Journal of Anaesthesia, 95(4), 434-441. https://doi.org/10.1093/bja/aei210
- Canada Controlled Drugs and Substances | http://laws-lois.justice.gc.ca/eng/acts/C-38.8/page-12.html#h-28
- Germany Controlled Substances | https://www.gesetze-im-internet.de/btmg_1981/anlage_iii.html
- Постановление Правительства РФ от 01.10.2012 N 1002 (ред. от 09.08.2019) | https://www.consultant.ru/cons/cgi/online.cgi?req=doc&base=LAW&n=331879&dst=100127&date=03.12.2019
- UK Controlled Drugs | https://www.gov.uk/government/publications/controlled-drugs-list--2/list-of-most-commonly-encountered-drugs-currently-controlled-under-the-misuse-of-drugs-legislation
- DEA Controlled Substances | https://www.deadiversion.usdoj.gov/schedules/orangebook/e_cs_sched.pdf