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Opioid

Fentanyl

Also called Fentanil, Sublimaze, Actiq, Durogesic, Duragesic, Fentora, Matrifen, Haldid, Onsolis, Instanyl, Abstral, Lazanda

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Common dose · Sublingual25–50 μg PW
Onset15–30 minutes PW
Total1–4 hours PW

Dosage

When sources disagree, both rows are shown as published. Nothing is averaged or merged.

Sublingual

SourceThresholdLightCommonStrongHeavy
PsychonautWiki5–10 μg PW10–25 μg PW25–50 μg PW50–75 μg PW75 μg+ PW

Bioavailability: 50% PW⚠ PsychonautWiki itself has flagged this text: citation needed.

Insufflated

SourceThresholdLightCommonStrongHeavy
PsychonautWiki5–10 μg PW10–25 μg PW25–50 μg PW50–75 μg PW75 μg+ PW⚠ The source row looks copy-pasted from another route. Check it before relying on it.
TripSit–10–25 ug TS25–50 ug TS50–75 ug+ TS–

Bioavailability: 89% PW⚠ PsychonautWiki itself has flagged this text: citation needed.

Transdermal

SourceThresholdLightCommonStrongHeavy
PsychonautWiki5–12 μg PW12–25 μg PW25–50 μg PW50–100 μg PW100 μg+ PW
TripSit–12.5 ug/hr TS25–50 ug/hr TS50–100 ug/hr TS–

Bioavailability: 92% PW⚠ PsychonautWiki itself has flagged this text: citation needed.

NOTE: Due to Fentanyl's high potency, it is incredibly difficult to measure safely, and so can easily lead to overdose. TS

TripSit dose text

TripSit's factsheet also states its doses as text.

Intranasal Light: 10-25ug Common: 25-50ug Strong: 50-75ug+ | Transdermal Light: 12.5ug/hr Common: 25-50ug/hr Strong: 50-100ug/hr | NOTE: Due to Fentanyl's high potency, it is incredibly difficult to measure safely, and so can easily lead to overdose. TS

What dose are you on? (self-reported, unverified)
Read this first. These numbers come from anonymous visitors typing in a box. Nobody checks them. People misjudge, mistype, troll, or take untested products of unknown strength. They are not a dose guide and never override the sourced table above. They exist only so the sourced ranges can be compared with what people say they take. If you are deciding what to take, use the sourced table, start low, and read the risks section.
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Duration

Route · sourceOnsetCome-upPeakOffsetTotalAfter-effects
Sublingual · PsychonautWiki15–30 minutes PW–––1–4 hours PW–
Insufflated · PsychonautWiki15–30 minutes PW–––1–4 hours PW–
Transdermal · PsychonautWiki2–4 hours PW–––48–72 hours PW–

TripSit factsheet

Onset
Buccal: 15-30 minutes · Insufflated: 5-15 minutes · Transdermal: 90-180 minutes TS
Duration
Buccal: 1-4 hours · Insufflated: 1-4 hours · Transdermal: 48-72 hours TS

Mixing

Acute combinations: what happens when these are taken close together. Entries backed by a medical journal or agency are listed first.

Backed by medical journals

Awaiting sourcePeer-reviewed reports on acute combinations, from PubMed and the journals the harm reduction sites cite.

PsychonautWiki also lists dangerous combinations shared across a whole group (opioids, serotonin syndrome) in a table this page does not copy. Read that list on PsychonautWiki.

TripSit combination chart

TripSit rates each pairing. Only pairings with a number carry a citation from TripSit. See the whole chart, with TripSit's note for every pairing.

Caution

Low Risk & Synergy

Low Risk & No Synergy

Risks and toxicity

Non-medical use of fentanyl by individuals without opiate tolerance can be very dangerous and has resulted in numerous deaths. It is potentially fatal at heavy dosages and even those with opiate tolerances are at high risk for overdoses. Once the fentanyl is in the user's system, it is extremely difficult to stop its course because of the nature of absorption. Because of the extremely high strength of pure fentanyl powder, it is very difficult to dilute appropriately, and often the resulting mixture may be far too strong and, therefore, very dangerous. It is also potentially lethal when mixed with depressants like alcohol or benzodiazepines.[23][24] PW

Like most opioids, pure fentanyl at appropriate dosages does not cause many long-term complications other than dependence and constipation. Outside of the extremely powerful addiction and physical dependence, the harmful or toxic aspects of opioid usage are exclusively associated with not taking the necessary precautions in regards to its administration, overdosing and using impure products. PW

Fentanyl is very potent and around 1000 times more permeable than morphine. Even though fentanyl uptake through skin is rather slow, unintentionally transporting the substance from the skin by touching the mouth, nose or eyes is dangerous.[25][26] PW

Heavy dosages of fentanyl can result in respiratory depression, leading onto fatal or dangerous levels of anoxia (oxygen deprivation). This occurs because the breathing reflex is suppressed by agonism of µ-opioid receptors proportional to the dosage consumed. PW

Fentanyl can also cause nausea and vomiting; a significant number of deaths attributed to opioid overdose are caused by aspiration of vomit by an unconscious victim. This is when an unconscious or semi-conscious user who is lying on their back vomits into their mouth and unknowingly suffocates. It can be prevented by ensuring that one is lying on their side with their head tilted downwards so that the airways cannot be blocked in the event of vomiting while unconscious (also known as the recovery position). In the case of an overdose, it is advised to administer a dose of naloxone intravenously or intramuscularly to counteract the effects of the substance. PW

It is strongly recommended that one use harm reduction practices when using this substance. PW

Tolerance and addiction potential

As with other opioids, the chronic use of fentanyl can be considered extremely addictive with a high potential for abuse and is capable of causing psychological and physical dependence among certain users. When addiction has developed, cravings and withdrawal symptoms may occur if a person suddenly stops their usage. PW

Tolerance to many of the effects of fentanyl 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). Fentanyl presents cross-tolerance with all other opioids, meaning that after the consumption of fentanyl all opioids will have a reduced effect. PW

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 substance in contrast to a familiar environment.[27][28] PW

TripSit factsheet

Warning
Risk of post-acute withdrawal effects, including depression, anxiety disorder, psychosis, suicidal ideation in extreme cases. TS

Testing

Awaiting sourceReagent reactions and test kit guidance from a harm reduction testing service.

Effects

Analgesiaeuphoriafeelings of relaxationsedative effectschanges in focusattentionrespiratory depressionnauseaconstipationdry mouthsomnolenceconfusionweaknesssweatingfatiguedizzinessanxiety TS

Overview

Fentanyl (also known as Fentanil and by the brand names Sublimaze, Actiq, Durogesic, Duragesic, Fentora, Matrifen, Haldid, Onsolis, Instanyl, Abstral, Lazanda among others) is a potent opioid substance of the anilidopiperidine class. It is a strong agonist at the μ-opioid receptors and approximately 40 to 50 times more potent than pharmaceutical grade (i.e. 100% pure) heroin and roughly 80 to 100 times more potent than morphine.[1–6] PW⚠ PsychonautWiki itself has flagged this text: citation needed.

Fentanyl is a synthetic opiate analgesic with a rapid onset and short duration of action. It is a strong agonist at the μ-opioid receptors and is historically used to treat breakthrough pain. Fentanyl is approximately 100 times more potent than Morphine, and is commonly used as a patch. Sometimes used as an adulterant for heroin, which has led to many overdose deaths. TS

Fentanyl is a highly potent synthetic opioid of the piperidine family, used primarily as pain medication. It is 50 to 100 times more potent than morphine. Its primary clinical use is in pain management for cancer patients and those recovering from surgery. Fentanyl is also used as a sedative for intubated patients. Fentanyl has a short duration of action. Fentanyl works by activating μ-opioid receptors. Brand names include Actiq, Duragesic, and Sublimaze, among others.[7–11] WP

Fentanyl was first synthesized by Paul Janssen in 1960 and was approved for medical use in the United States in 1968. In 2015, 1600 kg were used in healthcare globally. As of 2017, fentanyl was the most widely used synthetic opioid in medicine; in 2019, it was the 278th most commonly prescribed medication in the United States, with more than a million prescriptions. It is on the World Health Organization's List of Essential Medicines.[10][12–17] WP⚠ The source also gives this in other units.

The effects of fentanyl are similar to those of other opioids, causing sedation and analgesia at clinical doses. The most common adverse effects are respiratory depression, emesis, and asthenia. Bradycardia and apnea are uncommon side effects but are serious and can lead to death outside of clinical settings. Fentanyl exerts its actions as an agonist of the μ-opioid receptor and κ-opioid receptor. The μ-receptor agonism is responsible for the respiratory depression and generalized analgesia whilst the κ-receptor agonism is responsible for sedation and spinal analgesia. Fentanyl is a potent μ-receptor agonist but has less affinity for the κ-receptor. WP

Fentanyl is contributing to an epidemic of synthetic opioid drug overdose deaths in the United States. From 2011 to 2021, overdose deaths involving prescription opioid (natural and semi-synthetic opioids and methadone) per year remained stable, while synthetic opioid (primarily fentanyl) associated overdose deaths per year increased from 2,600 overdoses to 70,601. Fentanyl was involved in the most drug overdose deaths in the United States in 2018. The United States National Forensic Laboratory estimates fentanyl reports by federal, state, and local forensic laboratories increased from 4,697 reports in 2014 to 117,045 reports in 2020. Fentanyl is often mixed, cut, or ingested alongside other drugs, including cocaine and heroin. Fentanyl has been reported in pill form, including pills mimicking pharmaceutical drugs such as oxycodone. Mixing with other drugs or disguising as a pharmaceutical makes it difficult to determine the correct treatment in the case of an overdose, resulting in more deaths. Emerging adulterants have further complicated the evolving fentanyl supply.[9][18][19][20] WP

In an attempt to reduce the number of overdoses from taking other drugs mixed with fentanyl, drug testing kits, strips, and labs are available.[21][22] WP

History

History

Fentanyl was first synthesized in Belgium by Paul Janssen under the label of his relatively newly formed Janssen Pharmaceutica in 1959. It was developed by screening chemicals similar to pethidine (Demerol) for opioid activity. The widespread use of fentanyl triggered the production of fentanyl citrate (the salt formed by combining fentanyl and citric acid in a 1:1 stoichiometric ratio). Fentanyl citrate entered medical use as a general anesthetic in 1968, manufactured by McNeil Laboratories under the brand name Sublimaze.[29–33] WP

In the mid-1990s, Janssen Pharmaceutica developed and introduced into clinical trials the Duragesic patch, which is a formulation of an inert alcohol gel infused with select fentanyl doses, which are worn to provide constant administration of the opioid over 48 to 72 hours. After a set of successful clinical trials, Duragesic fentanyl patches were introduced into medical practice.[34] WP

Pharmacology

Classification

Fentanyl is a synthetic opioid in the phenylpiperidine family that has high protein binding and lipophilicity.[102][103] WP

Structure-activity

The structures of opioids share many similarities. Whereas opioids like codeine, hydrocodone, oxycodone, and hydromorphone are synthesized by simple modifications of morphine, fentanyl and its relatives are synthesized by modifications of meperidine. Meperidine is a fully synthetic opioid, and other members of the phenylpiperidine family like alfentanil and sufentanil are complex versions of this structure.[104] WP

Fentanyl is a weak base that is highly lipid-soluble, protein-bound, and protonated at physiological pH. All of these factors allow it to rapidly cross cellular membranes, contributing to its quick effect in the body and the central nervous system.[102][104][105] WP

Fentanyl analogs

Fentanyl analogs are types of fentanyl with various chemical modifications on any number of positions of the molecule, but still maintain, or even exceed, its pharmacological effects. Many fentanyl analogs are termed "designer drugs" because they are synthesized solely to be used illicitly. Carfentanil, a fentanyl analog, has an additional methyl ester group attached to the 4 position. Carfentanil is 20–30 times as potent as fentanyl and is common in the illicit drug chain. The drug is commonly used to tranquilize elephants and other large animals.[106] WP

Mechanism of action

Fentanyl acts on opioid receptors. These receptors are G-protein-coupled receptors, which contain seven transmembrane portions, intracellular loops, extracellular loops, intracellular C-terminus, and extracellular N-terminus. The extracellular N-terminus is important in differentiating different types of binding substrates. When fentanyl binds, downstream signaling leads to inhibitory effects, such as decreased cAMP production, decreased calcium ion influx, and increased potassium efflux. This inhibits the ascending pathways in the central nervous system to increase pain threshold by changing the perception of pain; this is mediated by decreasing propagation of nociceptive signals, resulting in analgesic effects.[104][107][108] WP⚠ Wikipedia itself has flagged this text: unreliable medical source?.

The affinity of fentanyl to the μ-opioid receptor is similar to that of morphine. The reasons for fentanyl's increased potency in vivo are unclear, however differences in efficacy and pharmacokinetics may be involved. It has high lipid solubility, allowing it to penetrate more easily the central nervous system. It attenuates "second pain" with primary effects on slow-conducting, unmyelinated C-fibers and is less effective on neuropathic pain and "first pain" signals through small, myelinated A-fibers.[102][104][105][109] WP

Fentanyl can produce the following clinical effects strongly, through μ-receptor agonism:[110] WP

It also produces sedation and spinal analgesia through Κ-receptor agonism.[110] WP

Detection in biological fluids

Fentanyl may be measured in blood or urine to monitor for abuse, confirm a diagnosis of poisoning, or assist in a medicolegal death investigation. Commercially available immunoassays are often used as initial screening tests, but chromatographic techniques are generally used for confirmation and quantitation. The Marquis Color test may also be used to detect the presence of fentanyl. Using formaldehyde and sulfuric acid, the solution will turn purple when introduced to opium drugs. Blood or plasma fentanyl concentrations are expected to be in a range of 0.3–3.0 μg/L in persons using the medication therapeutically, 1–10 μg/L in intoxicated people, and 3–300 μg/L in victims of acute overdosage. Paper spray-mass spectrometry (PS-MS) may be useful for initial testing of samples.[111][112] WP

Detection for harm reduction purposes

Fentanyl and fentanyl analogues can be qualitatively detected in drug samples using commercially available fentanyl testing strips or spot reagents. Following the principles of harm reduction, this test is to be used directly on drug samples as opposed to urine. To prepare a sample for testing, approximately 10 mg of the drug should be diluted into of water. Research in Dr. Lieberman's lab at the University of Notre Dame has reported false positive results on BTNX fentanyl testing strips with methamphetamine, MDMA, and diphenhydramine. The sensitivity and specificity of fentanyl test strips vary depending on the concentration of fentanyl tested, particularly from 10 to 250 ng/mL.[113][114][115] WP⚠ Part of this sentence could not be copied from the source. Open the source to read it in full.

Receptor binding · Wikipedia

Fentanyl at opioid receptors

Every row cites [101]

MOR (μ-opioid receptor)DOR (δ-opioid receptor)KOR (κ-opioid receptor)MOR:DOR:KOR
0.39 nM>1,000 nM255 nM1:>2564:654 WP⚠ The source table has only this one row.

Chemistry

Formula
C22H28N2O PC
CAS number
437-38-7 PC
Molar mass (g/mol)
336.5 PC
IUPAC name (computed by PubChem)
N-phenyl-N-[1-(2-phenylethyl)piperidin-4-yl]propanamide PC
SMILES
CCC(=O)N(C1CCN(CC1)CCC2=CC=CC=C2)C3=CC=CC=C3 PC
InChIKey
PJMPHNIQZUBGLI-UHFFFAOYSA-N PC
PubChem CID
3345

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References

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