XLR-11 (5"-fluoro-UR-144 or 5F-UR-144) is a drug that acts as a potent agonist for the cannabinoid receptorsCB1 and CB2 with EC50 values of 98 nM and 83 nM, respectively.[2] It is a 3-(tetramethylcyclopropylmethanoyl)indole derivative related to compounds such as UR-144, A-796,260 and A-834,735, but it is not specifically listed in the patent or scientific literature alongside these other similar compounds,[3][4] and appears to have not previously been made by Abbott Laboratories, despite falling within the claims of patent WO 2006/069196. XLR-11 was found to produce rapid, short-lived hypothermic effects in rats at doses of 3 mg/kg and 10 mg/kg, suggesting that it is of comparable potency to APICA and STS-135.[2]
XLR-11 was instead first identified by laboratories in 2012 as an ingredient in synthetic cannabis smoking blends, and appears to be a novel compound invented specifically for grey-market recreational use.[6]
The U.S. Drug Enforcement Administration (DEA) made XLR11 illegal under the Federal Controlled Substances act for the foreseeable future as of January 2024[update].[8]
It has also been banned in Florida as of 11 December 2012[update].[9]
^WO application 2006069196, Pace JM, Tietje K, Dart MJ, Meyer MD, "3-Cycloalkylcarbonyl indoles as cannabinoid receptor ligands", published 2006-06-29, assigned to Abbott Laboratories
^Frost JM, Dart MJ, Tietje KR, Garrison TR, Grayson GK, Daza AV, et al. (January 2010). "Indol-3-ylcycloalkyl ketones: effects of N1 substituted indole side chain variations on CB(2) cannabinoid receptor activity". Journal of Medicinal Chemistry. 53 (1): 295–315. doi:10.1021/jm901214q. PMID19921781.
^"XLR-11". Structural, chemical, and analytical data on controlled substances. Southern Association of Forensic Scientists (SAFS).
^Wilkinson SM, Banister SD, Kassiou M (2015). "Bioisosteric Fluorine in the Clandestine Design of Synthetic Cannabinoids". Australian Journal of Chemistry. 68: 4. doi:10.1071/CH14198.
^Trecki J, Gerona RR, Schwartz MD (July 2015). "Synthetic Cannabinoid-Related Illnesses and Deaths". The New England Journal of Medicine. 373 (2): 103–107. doi:10.1056/NEJMp1505328. PMID26154784.