Methadone

Fatal overdose may occur when opiates are combined with other depressants such as benzodiazepines, barbiturates, gabapentinoids, thienodiazepines, alcohol or other GABAergic substances.

It is strongly discouraged to combine these substances, particularly in common to heavy doses.

Summary sheet: Methadone

Methadone
Chemical Nomenclature
Common names	Methadone, Dolophine, Methadose
Systematic name	(RS)-6-(dimethylamino)-4,4-diphenylheptan-3-one
Class Membership
Psychoactive class	Opioid
Chemical class	Diphenylpropylamine
Routes of Administration
WARNING: Always start with lower doses due to differences between individual body weight, tolerance, metabolism, and personal sensitivity. See responsible use section. ⇣ Oral Dosage Bioavailability 40-99% Threshold 1 mg Light 3 - 5 mg Common 5 - 15 mg Strong 15 - 30 mg Heavy 30 mg + Duration Total 10 - 19 hours Onset 20 - 90 minutes Come up 2 - 4 hours Peak 4 - 6 hours Offset 4 - 6 hours After effects 1 - 24 hours DISCLAIMER: PW's dosage information is gathered from users and resources for educational purposes only. It is not a recommendation and should be verified with other sources for accuracy.
Interactions
MAOIs
Nitrous
PCP
Stimulants
SNRIs
Alcohol
Benzodiazepines
DXM
GHB
GBL
Ketamine
MXE
Tramadol
Grapefruit
MAOIs
Serotonin releasers
SSRIs
5-HTP

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.

Chemistry

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.

Methadone and its major metabolite, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), are often measured in urine as part of a drug abuse testing program, in plasma or serum to confirm a diagnosis of poisoning in hospitalized victims, or in whole blood to assist in a forensic investigation of a traffic or other criminal violation or a case of sudden death. Methadone usage history is considered in interpreting the results as a chronic user can develop tolerance to doses that would incapacitate an opioid-naive individual. Chronic users often have high methadone and EDDP baseline values.

The protonated form of methadone takes on an extended conformation, while the free base is more compact. In particular, it was found that there is an interaction between the tertiary amine and the carbonyl carbon of the ketone function (R₃N ••• >C=O) that limits the molecule's conformation freedom, though the distance (291 pm by X-ray) is far too long to represent a true chemical bond. However, it does represent the initial trajectory of attack of an amine on a carbonyl group and was an important piece of experimental evidence for the proposal of the Bürgi–Dunitz angle for carbonyl addition reactions.

Pharmacology

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.

The metabolic half life of methadone differs from its duration of action. The metabolic half life is 8 to 59 hours (approximately 24 hours for opioid-tolerant people, and 55 hours in opioid-naive people), as opposed to a half life of 1 to 5 hours for morphine. The length of the half life of methadone allows for exhibition of respiratory depressant effects for an extended duration of time in opioid-naive people.

Levomethadone (the L enantiomer) is a μ-opioid receptor agonist with higher intrinsic activity than morphine, but lower affinity. Dextromethadone (the S enantiomer) does not affect opioid receptors but binds to the glutamatergic NMDA (N-methyl-D-aspartate) receptor, and acts as an antagonist against glutamate. Methadone has been shown to reduce neuropathic pain, primarily through NMDA receptor antagonism. Glutamate is the primary excitatory neurotransmitter in the central nervous system. Acting as an NMDA antagonist may be one mechanism by which methadone decreases craving for opioids and tolerance, and has been proposed as a possible mechanism for its distinguished efficacy regarding the treatment of neuropathic pain.

Methadone also acted as a potent, noncompetitive α₃β₄ neuronal nicotinic acetylcholine receptor antagonist in rat receptors, expressed in human embryonic kidney cell lines.

Binding affinities (K_i)

Dextromethadone:

• Mu opioid agonist - 24.8 nM
• Kappa opioid agonist - 543 nM
• Delta opioid agonist - 1674 nM

According to a study published in the Journal of Pharmacology and Experimental Therapeutics, the dissociation constants (Kd) of Levomethadone at the different opioid receptors are as follows:

• Mu opioid agonist - 2.5 nM
• Kappa opioid agonist - 54 nM
• Delta opioid agonist - 97nM

Subjective effects

Disclaimer: The effects listed below cite the Subjective Effect Index (SEI), an open research literature based on anecdotal user reports and the personal analyses of PsychonautWiki contributors. As a result, they should be viewed with a healthy degree of skepticism.

It is also worth noting that these effects will not necessarily occur in a predictable or reliable manner, although higher doses are more liable to induce the full spectrum of effects. Likewise, adverse effects become increasingly likely with higher doses and may include addiction, severe injury, or death ☠.

Physical effects

• The general sensation of methadone can be described as one of immense euphoria, relaxation, anxiety suppression and pain relief.
  • Sedation - This leads to the trademark "nodding off" effect, but it is usually milder compared to that of diacetylmorphine (heroin)
  • Pain relief
  • Physical euphoria - This particular substance can be considered moderately intense, more commonly with the L-enantiomer, in its physical euphoria when compared with that of morphine or diacetylmorphine (heroin), and definitely stronger than that of other synthetic opioids such as tramadol. The sensation itself can be described as extreme feelings of intense physical comfort, extreme warmth, love and bliss.
  • Itchiness
  • 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.
  • Constipation
  • Cough suppression
  • Difficulty urinating
  • Nausea
  • Sedation
  • Pupil constriction
  • Decreased libido
  • Appetite suppression
  • Orgasm suppression
  • Abnormal heartbeat - A rare but potentially fatal side effect of methadone's potential to prolong the QT interval. Torsades de pointes is an abnormal heart rhythm which can lead to sudden cardiac death.

Cognitive effects

• • 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 the L-enantiomer (levomethadone) is way stronger and can be considered almost equal to diacetylmorphine. Both enantiomers, ultimately, are stronger than 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

Visual effects

• Suppressions

  • Double vision - At high doses, the eyes un-focus and re-focus uncontrollably. It appears to be caused by issues in depth perception, as by closing one eye the issue can be temporarily alleviated.

  Hallucinatory states

  • Internal hallucination - One may experience a state of semi-consciousness and hypnagogia during heavy dosage nodding which results in dream-like states and up to level 3 imagery. This is often accompanied by ill-defined geometry.

Experience reports

There are currently no anecdotal reports which describe the effects of this compound within our experience index. Additional experience reports can be found here:

• Erowid Experience Vaults: Methadone

Toxicity and harm potential

Table from the 2010 ISCD study ranking various drugs (legal and illegal) based on statements by drug-harm experts. Methadone was found to be the 12th overall most dangerous drug.

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.

Dangerous interactions

Warning: Many psychoactive substances that are reasonably safe to use on their own can suddenly become dangerous and even life-threatening when combined with certain other substances. The following list provides some known dangerous interactions (although it is not guaranteed to include all of them).

Always conduct independent research (e.g. Google, DuckDuckGo, PubMed) to ensure that a combination of two or more substances is safe to consume. Some of the listed interactions 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
• Stimulants - 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.
• 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 banisteriopsis caapi, syrian rue, phenelzine, selegiline, and moclobemide.
• Serotonin releasers - Such as MDMA, 4-FA, methamphetamine, methylone and αMT.
• SSRIs - Such as citalopram and sertraline
• SNRIs - Such as tramadol and venlafaxine
• 5-HTP

Legal status

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.
• Switzerland: Methadone is a controlled substance specifically named under Verzeichnis A. Medicinal use is permitted.
• United Kingdom: Methadone is a Class A, Schedule 2 drug in the United Kingdom.
• United States: Methadone is a Schedule II Controlled Substance.

See also

• Responsible use
• Opioid
• Tramadol
• Fentanyl
• Dextropropoxyphene

External links

• Methadone (Wikipedia)
• Methadone (Erowid Vault)
• Methadone (TiHKAL / Isomer Design)
• Methadone (DrugBank)
• Methadone (Drugs.com)
• Methadone (Drugs-Forum)