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Summary sheet: Fenethylline
Chemical Nomenclature
Common names Fenethylline, Captagon
Substitutive name amphetamin​oethyl​theophylline
Systematic name 1,3-dimethyl-7-[2-(1-phenylpropan-2-ylamino)ethyl]purine-2,6-dione
Class Membership
Psychoactive class Stimulant
Chemical class Amphetamine / Xanthine
Routes of Administration

WARNING: Always start with lower doses due to differences between individual body weight, tolerance, metabolism, and personal sensitivity. See responsible use section.

Bioavailability 39.2%[1]
Threshold 10 mg
Light 20 - 40 mg
Common 40 - 100 mg
Strong 100 - 200 mg
Heavy 200 mg +
Total 3 - 4 hours[1]
Onset 90 - 120 minutes[1]

DISCLAIMER: PW's dosage information is gathered from users and resources for educational purposes only. It is not a recommendation and should be verified with other sources for accuracy.


Fenethylline (also known as phenethylline, fenetylline, amphetamin​oethyl​theophylline, amfetyline, or by brand names including Captagon, Biocapton and Fitton) is a stimulant substance of the amphetamine class. It is a codrug for amphetamine and theophylline.

Fenethylline is most common in the Middle East under the name Captagon. Captagon is primarly produced in and exported from Syria, sponsored by the Syrian government under the Assad regime.[2] Captagon contributes to more than 90% of the foreign currency of Syria.[3] The annual Captagon merchandise of Syria is estimated to have been worth 57 billion US dollar in 2022.[4]

History and culture

Fenethylline was first synthesized by the german chemicals company Degussa AG in 1961

It was primarily marketed as a milder alternative to amphetamine, due to its lower potencial for raising blood pressure, making it ideal for patients with cardiovascular disease and was used for the treatment of children with ADHD and less commonly narcolepsy.[1]


Fenethylline's structure consists of an amphetamine molecule connected on the N position to a theophylline molecule at the R3 position by an ethyl group.


Conversion rate

24.5% of the weight of Fenethylline is metabolized to amphetamine and 13.7% to theophylline both of which are active stimulants.[1]

Subjective effects

Disclaimer: The effects listed below cite the Subjective Effect Index (SEI), an open research literature based on anecdotal user reports and the personal analyses of PsychonautWiki contributors. As a result, they should be viewed with a healthy degree of skepticism.

It is also worth noting that these effects will not necessarily occur in a predictable or reliable manner, although higher doses are more liable to induce the full spectrum of effects. Likewise, adverse effects become increasingly likely with higher doses and may include addiction, severe injury, or death ☠.

Physical effects

Experience reports

There are currently 0 experience reports which describe the effects of this substance in our experience index.

Dangerous interactions

Warning: Many psychoactive substances that are reasonably safe to use on their own can suddenly become dangerous and even life-threatening when combined with certain other substances. The following list provides some known dangerous interactions (although it is not guaranteed to include all of them).

Always conduct independent research (e.g. Google, DuckDuckGo, PubMed) to ensure that a combination of two or more substances is safe to consume. Some of the listed interactions have been sourced from TripSit.

  • Alcohol - Drinking alcohol on stimulants is considered risky because it reduces the sedative effects of the alcohol that the body uses to gauge drunkenness. This often leads to excessive drinking with greatly reduced inhibitions, increasing the risk of liver damage and increased dehydration. The effects of stimulants will also allow one to drink past a point where they might normally pass out, increasing the risk. If you do decide to do this then you should set a limit of how much you will drink each hour and stick to it, bearing in mind that you will feel the alcohol and the stimulant less.
  • GHB/GBL - Stimulants increase respiration rate allowing a higher dose of sedatives. If the stimulant wears off first then the depressant effects of the GHB/GBL may overcome the user and cause respiratory arrest.
  • Opioids - Stimulants increase respiration rate allowing a higher dose of opiates. If the stimulant wears off first then the opiate may overcome the patient and cause respiratory arrest.
  • Cocaine - The rewarding effects of cocaine are mediated by DAT inhibition, and an increase of exocytosis of dopamine through the cell membrane. Amphetamine reverses the direction of DAT and the direction vesicular transports within the cell by a pH mediated mechanism of displacement, thus excludes the regular mechanism of dopamine release through means of exocytosis because the effects Na+/K+ ATPase are inhibited. You will find cardiac effects with the combination of cocaine and amphetamine due to a SERT mediated mechanism from the subsequent activation of 5-HT2B, which is an effect of serotonin-related valvulopathy. Amphetamines generally cause hypertension in models of abuse, and this combination can increase the chances of syncope due to turbulent blood flow during valve operation. The rewarding mechanisms of cocaine are reversed by administration of amphetamine.[5][6]
  • Cannabis - Stimulants increase anxiety levels and the risk of thought loops and paranoia which can lead to negative experiences.
  • Caffeine - This combination of stimulants is generally considered unnecessary and may increase strain on the heart, as well as potentially causing anxiety and physical discomfort.
  • Tramadol - Tramadol and stimulants both increase the risk of seizures.
  • DXM - Both substances raise heart rate, in extreme cases, panic attacks caused by these substances have led to more serious heart issues.
  • Ketamine - Combining amphetamine and ketamine may result in psychoses that resemble schizophrenia, but not worse than the psychoses produced by either substance alone, but this is debatable. This is due to amphetamines ability to attenuated the disruption of working memory caused by ketamine. Amphetamine alone may result in grandiosity, paranoia, or somatic delusions with little to no effect on negative symptoms. Ketamine, however, will result in thought disorders, disruption of executive functioning, and delusions due to a modification of conception. These mechanisms are due to an increase of dopaminergic activity in the mesolimbic pathway caused by amphetamine due to its pharmacology effecting dopamine, and due to a disruption of dopaminergic functioning in the mesocortical pathways via NMDA antagonism effects of ketamine. Combining the two, you may expect mainly thought disorder along with positive symptoms.[7]
  • PCP - Increases risk of tachycardia, hypertension, and manic states.
  • Methoxetamine - Increases risk of tachycardia, hypertension, and manic states.
  • Psychedelics (e.g. LSD, mescaline, psilocybin) - Increases risk of anxiety, paranoia, and thought loops.
    • 25x-NBOMe - Amphetamines and NBOMes both provide considerable stimulation that when combined they can result in tachycardia, hypertension, vasoconstriction and, in extreme cases, heart failure. The anxiogenic and focusing effects of stimulants are also not good in combination with psychedelics as they can lead to unpleasant thought loops. NBOMes are known to cause seizures and stimulants can increase this risk.
    • 2C-T-x - Suspected of mild MAOI properties. May increase the risk of hypertensive crisis.
    • 5-MeO-xxT - Suspected of mild MAOI properties. May increase the risk of hypertensive crisis.
    • DOx
  • aMT - aMT has MAOI properties which may interact unfavorably with amphetamines.
  • MAOIs - MAO-B inhibitors can increase the potency and duration of phenethylamines unpredictably. MAO-A inhibitors with amphetamine can lead to hypertensive crises.

Legal status

Fenethylline became illegal in most countries in 1986 after being listed by the World Health Organization for international scheduling under the Convention on Psychotropic Substances.[8][1]

  • Australia: Fenethylline is a Schedule 9 prohibited substance.[9]
  • Brazil: Fenethylline is a Class A3 psychoactive substance.[10]
  • Canada: Fenethylline is a Schedule III drug in Canada.[11]
  • Germany: Fenethylline is a Anlage III(Schedule III) drug under the Betäubungsmittelgesetz(controlled substances law of Germany) and can only be obtained by prescription.[12]
  • United Kingdom: Fenethylline is a Class C drug in the United Kingdom.[13]
  • United States: Fenethylline is a Schedule I controlled substance in the United States.[citation needed]

See also

External links


  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 https://onlinelibrary.wiley.com/doi/full/10.1111/bcpt.12584
  2. https://web.archive.org/web/20230605043558/https://www.aljazeera.com/news/2023/5/9/what-is-captagon-the-addictive-drug-mass-produced-in-syria
  3. https://web.archive.org/web/20230106175927/https://www.spectator.co.uk/article/how-syria-became-the-worlds-most-profitable-narco-state
  4. https://web.archive.org/web/20230517053609/https://edition.cnn.com/2023/04/10/middleeast/syria-drugs-bargaining-chip-mime-intl/index.html
  5. Greenwald, M. K., Lundahl, L. H., Steinmiller, C. L. (December 2010). "Sustained Release d-Amphetamine Reduces Cocaine but not 'Speedball'-Seeking in Buprenorphine-Maintained Volunteers: A Test of Dual-Agonist Pharmacotherapy for Cocaine/Heroin Polydrug Abusers". Neuropsychopharmacology. 35 (13): 2624–2637. doi:10.1038/npp.2010.175. ISSN 0893-133X. 
  6. Siciliano, C. A., Saha, K., Calipari, E. S., Fordahl, S. C., Chen, R., Khoshbouei, H., Jones, S. R. (10 January 2018). "Amphetamine Reverses Escalated Cocaine Intake via Restoration of Dopamine Transporter Conformation". The Journal of Neuroscience. 38 (2): 484–497. doi:10.1523/JNEUROSCI.2604-17.2017. ISSN 0270-6474. 
  7. Krystal, J. H., Perry, E. B., Gueorguieva, R., Belger, A., Madonick, S. H., Abi-Dargham, A., Cooper, T. B., MacDougall, L., Abi-Saab, W., D’Souza, D. C. (1 September 2005). "Comparative and Interactive Human Psychopharmacologic Effects of Ketamine and Amphetamine: Implications for Glutamatergic and Dopaminergic Model Psychoses and Cognitive Function". Archives of General Psychiatry. 62 (9): 985. doi:10.1001/archpsyc.62.9.985. ISSN 0003-990X. 
  8. https://www.incb.org/incb/en/psychotropics/green-list.html
  9. https://www.legislation.gov.au/Details/F2019L01471
  10. https://www.in.gov.br/en/web/dou/-/resolucao-rdc-n-784-de-31-de-marco-de-2023-474904992
  11. https://laws-lois.justice.gc.ca/eng/acts/C-38.8/FullText.html
  12. https://www.gesetze-im-internet.de/btmg_1981/anlage_iii.html
  13. https://www.legislation.gov.uk/ukpga/1971/38/schedule/2