This article provides a comprehensive overview of the highly dangerous Schedule I narcotic U-47700, which is a μ-opioid receptor agonist. The article covers various aspects of U-47700, including its physico-chemical properties, pharmacology, and effects and symptoms of recreational use. Additionally, the article provides information on U-47700’s legal status, street names, prices, and approximate dosage. The article also includes a section on the synthesis of U-47700 and concludes with a summary of the current state of knowledge about this substance.

General Information About U-47700 Synthetic Cannabinoid [1]

Other synonyms names of U-47700 are: U4; pink heroin; pinky; pink; 6IY4WX208T; 3,4-Dichloro-N-[2-(dimethylamino)cyclohexyl]-N-methylbenzamide

IUPAC Name of U-47700: 3,4-dichloro-N-[(1R,2R)-2-(dimethylamino)cyclohexyl]-N-methylbenzamide

CAS numbers are 82657-23-6 (trans-R,R) and 121348-98-9 (stereoisomer
not specified)

Analogs of U-47700 are AH-7921; U-77891; U-50488; U-69,593; MT-45; U-51754; U-62066

U-47700 | A Brief Account Of The Near Future

Physico-Chemical Properties of U-47700 [1, 2]

  • Molecular Formula C16H22Cl2N2O
  • Molecular Weight 329.3
  • Melting point 97-98.5 oC
  • Boiling point 464.8±45.0 °C at 760 mmHg
  • Flash Point: 234.9±28.7 °C
  • Color/Form White or light pink powder
  • Solubility in water is 9.91 mg/L at 25 °C
  • U-47700 is lipophilic
  • Very soluble (527 g/L) at acidic pH
  • Structural formula present on Figure 1.

Figure 1. Structure of U-47700

Powder possible U-47700 can be seen in the picture provided in Figure 2.

Figure 2. Powders of U-47700

U-47700 and its structural isomer AH-7921 (Figure 3).

Figure 3. U-47700 and its structural isomer AH-7921

General Information of U-47700 in Recreational Use and Pharmacology [1,3,4,5]

U-47700, a synthetic opioid developed by The Upjohn Company in the 1970s, is a structural isomer of another opioid, AH7921. Despite its origins, U-47700 is classified as a highly toxic substance, with no recognized medical use. Similar to heroin and other designer opioids, this drug poses significant risks to users. Recently, U-47700 has gained attention in both the news and medical literature due to its potentially deadly effects [5].

Effects and symptoms of U-47700 Use

This report provides an analysis of postmortem concentrations of 3,4-dichloro-N-[2-(dimethylamino)cyclohexyl]-N-methylbenzamide (U-47700) in a fatal drug overdose case. The individual in question, a known drug abuser, was found unresponsive and not breathing in his bed, with drug paraphernalia indicating drug insufflation found in his room. Toxicology screening tests in peripheral blood identified U-47700 as the principal cause of death, with alprazolam abuse also being a contributing factor. The death was ruled accidental in nature [3].

In recent years, U-47700 has been used illicitly as a narcotic in both Europe and the USA. While it is currently not scheduled in the USA, it is a controlled substance in Finland and Sweden. U-47700 is a potent agonist of the µ-opioid receptor (MOR), with in vivo activity 7.5- to 12-fold greater than morphine. However, it was never clinically studied in humans. Although its pharmacological effects on humans have not been specifically investigated, user reports found on the internet suggest that its effects are similar to those of morphine and heroin. Fatalities related to U-47700 have been reported in the UK and Belgium. Like other potent opioid agonists, U-47700 can cause strong analgesia, sedation, euphoria, constipation, itching, and respiratory depression, which can be harmful or fatal [4].

Overdose cases involving U-47700 have resulted in patients presenting to the hospital with pulmonary edema, and those who survived an overdose typically exhibited decreased mental status, decreased respiratory rate, and tachycardia – all indicative of an opioid toxidrome [5]. Finally, U-47700, along with three of its analogs, has been shown to have greater relative potency than morphine (see Figure 4).

Figure 4. Initial in vivo of U-47700 with three analogs, relative to morphine [8]

Users have reported experiencing “Pink” effects, which are similar to the effects of opioids, including euphoria, feeling high, sedation, relaxation, numbness,U-47700 | A Brief Account Of The Near Future potent analgesia, severeU-47700 | A Brief Account Of The Near Future respiratory depression that may be fatal, pinpoint pupils, constipation, itching, drug tolerance, dependence, addiction, seizures, psychosis, and fatal overdose. According to reports received by the Drug Enforcement Administration (DEA) since 2015, there have been 46 deaths associated with U-47700 in six states: New Hampshire (1), New York (31), North Carolina (10), Ohio (1), Texas (2), and Wisconsin (1) [5].

Street Names, Prices and Approximate Dosage [4-7]

This substance is typically consumed by snorting, swallowing or injecting. U-47700, also known as “U4,” fake morphine, “pink,” or “pinky,” is a highly potent synthetic opioid that resembles a white or light pink powder. “Grey Death” is a combination of U-47700, heroin, and fentanyl, although the amount of each drug in the mixture varied from sample to sample. It is often sold in bags or pressed into pills that resemble legal painkillers. Its abuse is similar to that of heroin, prescription opioids, and designer opioids. 3,4-Dichloro-N-[2-(dimethylamino)cyclohexyl]-N-methylbenzamide (U-47700) is a potent synthetic µ-opioid analgesic that costs $40 per gram and $2400 per kilogram [6]. A liquid form labeled as containing 20 mg/mL is sold in 15 mL bottles priced at $35.99 [6].

One death resulting from mixed drug intoxication has been reported, which also involved the use of other drugs of abuse such as mexedrone, amphetamine, and ketamine, as well as therapeutic medications such as quetiapine, amitriptyline, and naproxen. Around the same time, a fatality was described (in combination with fentanyl and sertraline) with blood and urine U-47700 concentrations of 13.8 and 71.0 ng/mL, respectively. A non-fatal intoxication in central California was presented with a hospital admission serum concentration of 7.6 ng/mL, again in combination with fentanyl and other drugs such as benzoylecgonine, sertraline, gabapentin, hydrocodone, and acetaminophen [4]. The most common routes of ingestion were by insufflation and intravenous injection [5]. The dosing of U-47700 is as follows: Light 5-7.5 mg; Common 7.5-15 mg; Strong 15-25 mg; Heavy 25+ mg [7].

Legal Status

U-4700 is classified as a narcotic and falls under Schedule I of the Drug Enforcement Administration’s (DEA) list of controlled substances. Substances under Schedule I are considered to have a high potential for abuse, no currently accepted medical use in the United States, and a lack of accepted safety for use under medical supervision. After being marketed as a designer drug, U-47700 was eventually banned in Sweden on January 26, 2016.

Synthesis of 3,4-dichloro-N-[(1R,2R)-2-(dimethylamino)cyclohexyl]-N-methylbenzamide [8]

The detailed article [8] presents a unique and speedy approach involving two steps that leads to a blend of trans-diastereomers of 6. The process starts with 7-methyl-7-azabicyclo[4.1.0]heptane. All the analogs that were analyzed were found to be a 50:50 mix of the trans-(R,R) and trans-(S,S)-diastereomers. The general synthesis of this compound can be seen in the diagram provided in Figure 5.

Figure 5. General scheme of U-47700 synthesis


U-47700 is a synthetic opioid that has no recognized medical use and poses similar risks as other opioids like heroin and designer drugs. It is a structural isomer of AH7921, another opioid. Interestingly, U-47700 is also the name of a Dutch sci-fi short film released in 2021. The movie depicts characters addicted to a new drug that contains U-47700 as one of its components. The film was directed by Erasmo de la Parra.


  1. https://pubchem.ncbi.nlm.nih.gov/compound/13544016#section=Molecular-Formula
  2. https://www.chemspider.com/Chemical-Structure.23113403.html
  3. Iain M McIntyre, Ray D Gary etc. A Fatality Related to the Synthetic Opioid U-47700: Postmortem Concentration Distribution. Journal of Analytical Toxicology, 2017, 41, pp. 158–160. DOI: 10.1093/jat/bkw124 https://pubmed.ncbi.nlm.nih.gov/27798077/
  4. https://pubchem.ncbi.nlm.nih.gov/source/hsdb/8388
  5. Kerry Anne Rambaran, Steven W. Fleming etc. U-47700: A CLINICAL REVIEW OF THE LITERATURE. SELECTED TOPICS: TOXICOLOGY, 2017, VOLUME 53, ISSUE 4, P509-519. DOI:https://doi.org/10.1016/j.jemermed.2017.05.034 https://www.jem-journal.com/article/S0736-4679(17)30480-8/fulltext
  6. K. Domanskia, K.C. Kleinschmidt etc. Two cases of intoxication with new synthetic opioid, U-47700. CLINICAL TOXICOLOGY, 2017, VOL. 55, N. 1, 46–50. http://dx.doi.org/10.1080/15563650.2016.1209763 https://www.tandfonline.com/doi/full/10.1080/15563650.2016.1209763?scroll=top&needAccess=true&role=tab
  7. Timothy P Rohrig, Samuel A Miller, Tyson R Baird U-47700: A Not So New Opioid. Journal of Analytical Toxicology, 2018;42:e12–e14. doi: 10.1093/jat/bkx081 https://academic.oup.com/jat/article/42/1/e12/4430779
  8. KWAKU Kyei-Baffour, and Craig W Lindsley DARK Classics in Chemical Neuroscience: U-47700. ACS Chem. Neurosci. 2020, 11, 23, 3928–3936. https://doi.org/10.1021/acschemneuro.0c00330 https://pubs.acs.org/doi/abs/10.1021/acschemneuro.0c00330