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Pethidine
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Revision as of 20:34, 10 August 2019 by >LockPicker(Format)
WARNING: Always start with lower doses due to differences between individual body weight, tolerance, metabolism, and personal sensitivity. See responsible use section.
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 opioidanalgesic 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.
Pethidine is an opioid in the phenylpiperidine class.
Pharmacology
Opioids exert their effects by binding to and activating the μ-opioidreceptor. 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 acetylcholinereceptorantagonist. Pethidine is also a dopaminereuptake 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
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 PsychonautWikicontributors. 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 ☠. Many users note that they find pethidine just as, or more euphoric than oxycodone.[3]
Physical effects
The general sensation of pethidine can be described as one of euphoria, relaxation, anxiety suppression and pain relief.
Physical euphoria - This particular substance can be considered as very intense in its physical euphoria. 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.
Seizures - High doses of pethidine may cause seizures. This is because of its metabolite norpethidine.
Cognitive effects
Cognitive euphoria - This particular substance can be considered as very intense in its cognitive euphoria. The sensation itself can be described as powerful and overwhelming feeling of emotional bliss, contentment, and happiness.
Acuity suppression - Pethidine is a muscarinic acetylcholine receptor antagonist which may cause blurred vision at high doses.
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:
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 [[Toxicity::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]
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 [[Cross-tolerance::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
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.
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.
Stimulants - 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.
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.
. eISSN 1471-6771. ISSN 0007-0912. OCLC 01537271. PMID 16051647.