4′-Fluoro-4-methylaminorex, commonly called 4F-MAR or 4-FPO, is a recreational designer drug from the substituted aminorex class. This compound is known for its stimulant properties. Its presence was initially identified in Slovenia in the year 2018. Notably, it was subjected to legal prohibition in Italy in March 2020.

IUPAC name
CAS Number1364933-64-1 
PubChem CID134080816
Chemical and physical data
Molar mass194.209 g·mol−1


  • What is 4′-Fluoro-4-methylaminorex (4F-MAR)?
  • 4′-Fluoro-4-methylaminorex, often abbreviated as 4F-MAR or 4-FPO, is a synthetic recreational designer drug that falls into the substituted aminorex family. It is primarily known for its stimulant effects.
  • When was 4F-MAR first discovered?
  • The presence of 4′-Fluoro-4-methylaminorex was initially detected in Slovenia in the year 2018.
  • Is 4F-MAR legal to use and possess?
  • The legal status of 4F-MAR varies from country to country. It is important to note that it has been banned in several nations, such as Italy, where it was made illegal in March 2020. Always check the local laws and regulations regarding the possession and use of designer drugs in your area.
  • What are the effects of 4F-MAR?
  • As a stimulant, 4F-MAR can produce effects similar to other substances in its class. These effects may include increased alertness, energy, and a sense of euphoria. However, it can also carry risks and side effects, so it should be cautiously used.
  • Is 4F-MAR safe to use?
  • The safety of 4F-MAR is not well-documented, and its use carries potential health risks. The lack of research and regulation means the purity and contents of products sold as 4F-MAR vary. As with any recreational substance, there are inherent dangers, including the risk of addiction, adverse reactions, or other health complications. Its use is discouraged.
  • Where can I find more information about 4F-MAR?
  • It’s essential to rely on credible sources for information about any substance. For up-to-date and accurate information about 4F-MAR, you may refer to scientific journals, government health agencies, or substance-specific resources.
  • Is there ongoing research on 4F-MAR?
  • Research into the effects and potential risks of 4F-MAR may continue, but its status as a designer drug is subject to regulatory changes in many regions. Be sure to stay informed about developments in the field.
  • Is 4F-MAR used for any legitimate medical purposes?
  • 4F-MAR is not approved for medical use and is classified as a designer drug. Medical professionals do not prescribe it.
  • What precautions should I take if I come across 4F-MAR?
  • If you encounter or suspect the use of 4F-MAR or similar designer drugs, it is advisable to report it to the appropriate authorities. For your safety, avoid contacting or consuming substances with unknown origins or composition.
  • Is 4F-MAR addictive?
  • As a stimulant, 4F-MAR has the potential for addiction, like many other substances in its class. Continuous or heavy use can lead to dependence and withdrawal symptoms. Being aware of these risks is crucial if you are considering its use.


  1. Fabregat-Safont D, Carbón X, Ventura M, Fornís I, Hernández F, Ibáñez M (June 2019). “Characterization of a recently detected halogenated aminorex derivative: para-fluoro-4-methylaminorex (4’F-4-MAR)”. This study provides an in-depth analysis of para-fluoro-4-methylaminorex, a halogenated aminorex derivative, shedding light on its properties and characteristics. It can be a valuable resource for those seeking to understand this compound further.
  2. Maier J, Mayer FP, Brandt SD, Sitte HH (October 2018). “DARK Classics in Chemical Neuroscience: Aminorex Analogues”. This publication explores aminorex analogues, including their chemical properties and their relevance in the field of chemical neuroscience. The study discusses various aspects of these compounds, contributing to the knowledge in this area.
  3. Seibert E, Kunert O, Pferschy-Wenzig EM, Schmid MG. Characterization of Three Novel 4-Methylaminorex Derivatives Applied as Designer Drugs. In this recent research, three new 4-methylaminorex derivatives, employed as designer drugs, are thoroughly characterized. This study provides insights into the properties and potential implications of these compounds.
  4. “DECRETO 13 marzo 2020. Aggiornamento delle tabelle contenenti l’indicazione delle sostanze stupefacenti e psicotrope.” This official decree, issued in March 2020 by the Republic of Italy, addresses updates to the tables listing narcotic and psychotropic substances. It specifically mentions the inclusion of new psychoactive substances in Table I and Table IV, providing information on legal regulations regarding these substances in Italy.

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