Pethidine

Summary sheet: Pethidine

Pethidine
Chemical Nomenclature
Common names	Pethidine, Meperidine, Demerol, Dolantin, Dolcontral
Systematic name	Ethyl 1-methyl-4-phenylpiperidine-4-carboxylate
Class Membership
Psychoactive class	Opioid
Chemical class	Phenylpiperidine
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 50-60% Threshold 25 - 50 mg Light 50 - 100 mg Common 100 - 200 mg Strong 200 - 400 mg Heavy 400 mg + Duration Onset 30 - 60 minutes Peak 4 - 6 hours After effects 2 - 10 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.

Pethidine, known as meperidine in the United States (sold under the brand name Demerol), is a synthetic opioid analgesic used for the treatment of moderate to severe pain. Compared to traditional opioids such as morphine, pethidine was originially thought to be much safer and have less potential for abuse. It was later discovered that pethidine is significantly less safe than morphine and its metabolite norpethidine can be extremely toxic.

Chemistry

Pethidine is an opioid in the phenylpiperidine class.

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 pethidine can vary from 50% to around 60%.

Compared to traditional opioids, pethidine has a very unique pharmacological profile. In addition to being an opioid, pethidine is also a muscarinic acetylcholine receptor antagonist. Pethidine is also a dopamine reuptake inhibitor and norepinephrine reuptake inhibitor. Pethidine is a κ-opioid agonist and its metabolite norpethidine is also an extremely powerful serotonin reuptake inhibitor.^[2]

Subjective effects

The effects listed below are based upon the subjective effects index and personal experiences of PsychonautWiki contributors. These effects should be taken with a grain of salt and will rarely (if ever) occur all at once, but heavier doses will increase the chances of inducing a full range of effects. Likewise, adverse effects become much more likely on higher doses and may include serious injury or death. Many users note that they find pethidine just as, or more euphoric than oxycodone.^[3]

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: Pethidine

Toxicity and harm potential

Pethidine has a high 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.

One of pethdine's metabolites, norpethidine has little to no opioid action, but is known to cause seizures. Pethidine should not be taken during benzodiazepine withdrawals as this can potentially cause seizures. In 1984, Libby Zion, a teenager was brought to the emergency room due to a "flu-like" ailment. She was previously prescribed and taking phenelzine, a monoamine oxidase inhibitor, which in combination caused fatal serotonin syndrome.^[4]

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 pethidine 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 pethidine 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). Pethidine presents cross-tolerance with all other opioids, meaning that after the consumption of pethidine 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.^[5] 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.^[6]

Dangerous interactions

Although many psychoactive substances are safe to use on their own, they can become dangerous or even life-threatening when taken with other substances. The list below contains some potentially dangerous combinations, but may not include all of them. Certain combinations may be safe in low doses but still increase the possibility of injury of death. Independent research should always be conducted to ensure that a combination of two or more substances is safe before consumption.

• Depressants (1,4-Butanediol, 2M2B, alcohol, benzodiazepines, barbiturates, GHB/GBL, methaqualone, opioids) - This combination potentiates the muscle relaxation, amnesia, sedation, and respiratory depression caused by one another. At higher doses, it can lead to a sudden, unexpected loss of consciousness along with a dangerous amount of depressed respiration. There is also an increased risk of suffocating on one's vomit while unconscious. If nausea or vomiting occurs before a loss of consciousness, users should attempt to fall asleep in the recovery position or have a friend move them into it.

• Stimulants - It can be dangerous to combine depressants with stimulants due to the risk of accidental excessive intoxication. Stimulants mask the sedative effect of depressants, which is the main factor most people use to gauge their level of intoxication. Once the stimulant effects wear off, the effects of the depressant will significantly increase, leading to intensified disinhibition, motor control loss, and dangerous black-out states. This combination can also potentially result in severe dehydration if one's fluid intake is not closely monitored. If choosing to combine these substances, one should strictly limit themselves to a pre-set schedule of dosing only a certain amount per hour until a maximum threshold has been reached.

• Dissociatives - This combination can unpredictably potentiate the amnesia, sedation, motor control loss and delusions that can be caused by each other. It may also result in a sudden loss of consciousness accompanied by a dangerous degree of respiratory depression. If nausea or vomiting occurs before consciousness is lost, users should attempt to fall asleep in the recovery position or have a friend move them into it.
• Psychedelics - Pethidine is known to lower seizure threshold^{[citation needed]} and psychedelics also cause occasional seizures.^{[citation needed]}

Serotonin syndrome risk

Pethidine is known to have a significantly increased chance of causing serotonin syndrome than other serotonergic opioids such as tramadol.^{[citation needed]} 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^[7]
• 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
• 5-HTP

Legal issues

• United States: Pethidine is a Schedule II Controlled Substance.^[8]
• United Kingdom: Pethidine is a Class A, Schedule 2 drug in the United Kingdom.^[9]

See also

• Responsible use
• Opioid
• Tramadol
• Fentanyl
• Dextropropoxyphene
• Haloperidol

External links

• Pethidine (Wikipedia)
• Pethidine (Erowid Vault)
• Pethidine (Isomer Design)

References