Butyrfentanyl or butyrylfentanyl is a potent short-acting synthetic

opioid Opioids are substances that act on opioid receptors to produce morphine-like effects. Medically they are primarily used for pain relief, including anesthesia. Other medical uses include suppression of diarrhea, replacement therapy for opioid us ...

analgesic An analgesic drug, also called simply an analgesic (American English), analgaesic (British English), pain reliever, or painkiller, is any member of the group of drugs used to achieve relief from pain (that is, analgesia or pain management). It ...

drug A drug is any chemical substance that causes a change in an organism's physiology or psychology when consumed. Drugs are typically distinguished from food and substances that provide nutritional support. Consumption of drugs can be via insuffla ...

. It is an

analog Analog or analogue may refer to: Computing and electronics * Analog signal, in which information is encoded in a continuous variable ** Analog device, an apparatus that operates on analog signals *** Analog electronics, circuits which use analog ...

fentanyl Fentanyl, also spelled fentanil, is a very potent synthetic opioid used as a pain medication. Together with other drugs, fentanyl is used for anesthesia. It is also used illicitly as a recreational drug, sometimes mixed with heroin, cocaine ...

with around one quarter of its potency. One of the first mentions of this drug can be found in document written by The College on Problem of Drug Dependence, where it is mentioned as ''N''-butyramide fentanyl analog.The College on Problem of Drug Dependence
, Foreword to the Drug Evaluation Committee (DEC) Analgesic, Stimulant, and Depressant Drug Indices This document also states that the article describing its clinical effects (analgesic studies, μ-, δ-, κ-opioid receptor binding, and ''

in vitro ''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in biology an ...

'' measures of drug efficacy, antinociceptive, and narcotic properties) was published in 1987. It is an agonist for the

μ-opioid receptor The μ-opioid receptors (MOR) are a class of opioid receptors with a high affinity for enkephalins and beta-endorphin, but a low affinity for dynorphins. They are also referred to as μ(''mu'')-opioid peptide (MOP) receptors. The prototypical � ...

s.Utilization of a radioreceptor assay for the analysis of fentanyl analogs in urine
Mario Enrique Alburges Butyrfentanyl has no current legitimate clinical applications; however, it is being sold as a

designer drug A designer drug is a structural or functional analog of a controlled substance that has been designed to mimic the pharmacological effects of the original drug, while avoiding classification as illegal and/or detection in standard drug tests. Des ...

. Side effects of fentanyl analogs are similar to those of fentanyl itself, which include

itching Itch (also known as pruritus) is a sensation that causes the desire or reflex to scratch. Itch has resisted many attempts to be classified as any one type of sensory experience. Itch has many similarities to pain, and while both are unpleasan ...

nausea Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. While not painful, it can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the ...

, and potentially serious

respiratory depression Hypoventilation (also known as respiratory depression) occurs when ventilation is inadequate (''hypo'' meaning "below") to perform needed respiratory gas exchange. By definition it causes an increased concentration of carbon dioxide (hypercapnia ...

which can be life-threatening. Fentanyl analogs have killed hundreds of people throughout Europe and the former Soviet republics since the most recent resurgence in use began in Estonia in the early 2000s, and novel derivatives continue to appear.

Pharmacokinetics

Butyrfentanyl binds to the opioid receptor. During the studies of

inhibition of specific Hfentanyl binding to the opioid receptor, the order of analogues was: (±)-''cis''-3-methylfentanyl > fentanyl = alpha-methylfentanyl > butyrylfentanyl > benzylfentanyl. The studies in inhibition studies on binding affinity achieved the same order of analogues. It means that butyrfentantyl is a less potent opioid-agonist than fentanyl. On the other side, during in vitro studies of cross-reactivity with the fentanyl

antibody An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...

between fentanyl and the fentanyl analogs examined, revealed order: fentanyl = butyrylfentanyl > (±)-''cis''- 3-methylfentanyl > benzylfentanyl > alpha-methylfentanyl. High cross-reactivity may be the effect of the shape of the molecule - the shape of butyrfentanyl is closest to the original fentanyl molecule, which makes it easy to bind by fentanyl antibodies. The opioid

receptor affinity In chemistry, biochemistry, and pharmacology, a dissociation constant (K_D) is a specific type of equilibrium constant that measures the propensity of a larger object to separate (dissociate) reversibly into smaller components, as when a complex f ...

of fentanyl and its analogs was determined from their inhibitory potency in a binding assay with Hfentanyl as the radioligand. The Ki value for butyrfentanyl was Ki=32 ± 4.1 nM. Comparing to fentanyl's Ki (Ki=1.06 ± 0.15 nM), butyrfentanyl's ability to displace Hfentanyl is low and it requires high concentrations of the drug. Studies on urinary excretion revealed that almost all of the injected butyrfentanyl was excreted or metabolized within the first 3 h after injection, and only very low concentrations were still detectable after 3 h. Urinary concentrations of butyrylfentanyl from animals injected with 15 μg/kg and 45 μg/kg i.v. were measured by two techniques: radioreceptorassay and gas chromatography/mass spectrometry ( GC/MS).

Legal status

There was a proposal being discussed by the UN Commission on Narcotic Drugs (CND) to include butyrfentanyl in Schedule 1 of the 1961 Single Convention on Narcotic Drugs which was passed 16 March 2017.

United Kingdom

Butyrfentanyl is illegal in the United Kingdom as it is a modification of fentanyl "by replacement of the N-propionyl group by another acyl group".

United States

As of May 2016, butyrfentanyl is a Schedule I controlled substance in the United States.

Pharmacokinetics

Legal status

United Kingdom

United States

China

Switzerland

See also

References

Further reading