Fenethylline

Fenethylline (BAN, USAN) is a codrug of amphetamine and theophylline and a prodrug to both. It is also spelled phenethylline and fenetylline (INN); other names for it are amphetaminoethyltheophylline and amfetyline. The drug was marketed for use as a psychostimulant under the brand names Captagon, Biocapton, and Fitton. It is now illegal in most countries and is produced primarily for illicit use. Syria is considered to be the world's largest producer of the drug, accounting for about 80% of the global supply.

History
Fenethylline was first synthesized by the German pharmaceutical firm Degussa AG in 1961 and used for around 25 years as a milder alternative to amphetamine and related compounds. Although there are no FDA-approved indications for fenethylline, it was used in the treatment of "hyperkinetic children", in what would now be called attention deficit hyperactivity disorder, and, less commonly, for narcolepsy and depression. One of the main advantages of fenethylline was that it does not increase blood pressure to the same extent as an equivalent dose of amphetamine and so could be used in patients with cardiovascular conditions.

Fenethylline was considered to have fewer side effects and less potential for abuse than amphetamine. Nevertheless, fenethylline was listed in 1981 as a schedule I controlled substance in the United States, and it became illegal in most countries in 1986 after being listed by the World Health Organization for international scheduling under the Convention on Psychotropic Substances, even though the actual incidence of fenethylline abuse was quite low.

Pharmacology
The fenethylline molecule results when theophylline is covalently linked with amphetamine by an alkyl chain.

Fenethylline is metabolized by the body to form two drugs, amphetamine (24.5% of oral dose) and theophylline (13.7% of oral dose), both of which are active stimulants. The physiological effects of fenethylline therefore seem to result from a combination of these two compounds,  although how, it is not entirely clear, and seems to involve a synergistic effect between amphetamine and theophylline produced following metabolism. The pharmacological actions of fenethylline before cleavage also remain poorly established, though it appears to act directly at several serotonin receptors.

Abuse and illegal trade
Abuse of fenethylline of the brand name Captagon is common in the Middle East, and counterfeit versions of the drug continue to be available despite its illegality. Captagon is much less common outside of the Middle East, to the point that police may not recognize the drug. Captagon production and export has become a big industry sponsored by the Syrian government, with revenue from its exports contributing to more than 90% of its foreign currency. The Assad regime's annual Captagon merchandise is estimated to have been worth US$57 billion in 2022, about three times the total trade of all Mexican drug barons.

Many of these counterfeit "Captagon" tablets contain other amphetamine derivatives that are easier to produce, but are pressed and stamped to look like Captagon pills. Some counterfeit Captagon pills analysed do contain fenethylline, indicating that illicit production of this drug continues to take place. These illicit pills often contain "a mix of amphetamines, caffeine[,] and various fillers", which are sometimes referred to as "captagon" (with a lowercase "c").

Fenethylline is a popular drug in Western Asia, and American media outlet CNN reported in 2015 that it is allegedly used by militant groups in Syria. Later research demonstrated that it was the Syrian government of Bashar al-Assad that has been financing Captagon production and sponsoring networks of its drug dealers in coordination with the Syrian intelligence. It is manufactured locally by a cheap and simple process. In July 2019 in Lebanon, captagon was sold for $1.50 to $2.00 a pill. In 2021 in Syria, low-quality pills were sold locally for less than $1, while high-quality pills are increasingly smuggled abroad and may cost upwards of $14 each in Saudi Arabia.

According to some leaks, militant groups export the drug in exchange for weapons and cash. According to Abdelelah Mohammed Al-Sharif, secretary general of the National Committee for Narcotics Control and assistant director of Anti-Drug and Preventative Affairs, forty percent of users between the ages of twelve and twenty-two in Saudi Arabia are addicted to fenethylline. In 2017, Captagon was the most popular recreational drug in the Arabian Peninsula.

In October 2015, a member of the Saudi royal family, Prince Abdel Mohsen Bin Walid Bin Abdulaziz, and four others were detained in Beirut on charges of drug trafficking after airport security discovered two tons of Captagon (fenethylline) pills and some cocaine on a private jet scheduled to depart for Riyadh, the Saudi capital. The following month, Agence France-Presse reported that the Turkish authorities had seized two tonnes of Captagon—about eleven million pills—during raids in the Hatay region on the Syrian border. The pills had been produced in Syria and were being shipped to countries in the Arab states of the Persian Gulf.

In December 2015, the Lebanese Army announced that it had discovered two large-scale drug production workshops in the north of the country and seized large quantities of Captagon pills. Two days earlier, three tons of Captagon and hashish were seized at Beirut Airport, concealed in school desks being exported to Egypt.

Traces of the drug were found on a mobile phone used by Mohamed Lahouaiej Bouhlel, a French-Tunisian who killed eighty-four civilians in Nice on Bastille Day 2016.

In May 2017, French customs at Charles de Gaulle Airport seized 750,000 Captagon pills being transported from Lebanon to Saudi Arabia. In 2017, two other consignments of pills were found at Charles de Gaulle Airport: in January, heading for the Czech Republic, and in February, hidden in steel moulds. Further investigation showed that the seized products mainly contained a mixture of amphetamine and theophylline.

In January 2018, Saudi Arabia seized 1.3 million Captagon pills at the Al-Haditha crossing near the border with Jordan. In December 2018, Greece intercepted a Syrian ship sailing for Libya, carrying six tonnes of processed cannabis and three million Captagon pills. In July 2019, a shipment of thirty-three million Captagon pills, weighing 5.25 tonnes, was seized in Greece coming from Syria. In July 2019, eight hundred thousand Captagon pills were found on a boat in the United Arab Emirates. In August 2019, Saudi customs at Al-Haditha seized 2,579,000 Captagon pills found inside a truck and a private vehicle.

In February 2020, the UAE found thirty-five million Captagon pills in a shipment of electric cables from Syria to Jebel Ali. In April 2020, Saudi Arabia seized 44.7 million Captagon pills smuggled from Syria, and citing drug smuggling concerns, imposed an import ban on fruits and vegetables from Lebanon, causing the price of Lebanese lettuce to plummet. On 1 July 2020, an anti-drug operation coordinated in Italy by the Italian Guardia di Finanza and Customs and Monopolies Agency seized fourteen tonnes of amphetamines, labeled as Captagon, smuggled from Syria and initially thought by the Italian authorities to have been produced by ISIS,  which were found in three shipping containers filled with around 84 million pills, in the southern port of Salerno.

In November 2020, Egypt seized two shipments of Captagon pills at Damietta port coming from Syria. The first had 3,251,500 tablets, while the second contained 11 million tablets. In December 2020, Italian authorities seized about 14 tonnes of Captagon arriving from Latakia, Syria, and heading towards Libya, numbering about 85 million pills, worth around $1 billion.

In January 2021, Egyptian authorities seized eight tons of Captagon and another eight tons of hashish at Port Said, from a shipment that arrived from Lebanon. In February 2021, Lebanese customs seized at Beirut port a shipment of 5 million Captagon pills hidden in a tile-making machine, intended for Greece and Saudi Arabia. In April 2021, Saudi authorities discovered 5.3 million Captagon pills hidden in fruits imported from Lebanon.

Production in Syria
The drug has played a role in the Syrian civil war. The production and sale of fenethylline generates large revenues which are likely used to fund weapons, and fenethylline is used as a stimulant by combatants. Poverty and international sanctions that limit legal exports are contributing factors.

In May 2021, the UK newspaper The Guardian described the effects of Captagon production in Syria on the economy as a dirty business that is creating a near-narco-state. Drug money flowing into Syria is destabilizing legitimate businesses, positioning it as the global centre of Captagon production, with increased industrialization, adaptation, and technical sophistication. In June 2021, Saudi authorities at Jeddah port seized fourteen million Captagon tablets hidden inside a shipment of iron plates coming from Lebanon. In the same month, Saudi authorities seized a shipment of 4.5 million Captagon pills, smuggled inside several orange cartons, at Jeddah port. In July 2021, Saudi customs discovered 2.1 million Captagon pills at Al-Haditha hidden in a tomato paste shipment.

The New York Times reported in December 2021 that the Syrian Army's elite 4th Armoured Division, commanded by Maher al-Assad, whose brother Bashar al-Assad is the ruler of Syria, oversees much of the production and distribution of Captagon, among other drugs. The unit controls manufacturing facilities, packing plants, and smuggling networks all across Syria, and had started to deal in crystal meth. The division's security bureau, headed by Maj. Gen. Ghassan Bilal, provides protection for factories and along smuggling routes to the port city Latakia and to border crossings with Jordan and Lebanon. Jihad Yazigi, editor of The Syria Report, reported that Captagon "has probably become Syria's most important source of foreign currency."

Military use
Captagon is a major stimulant used amongst some jihadist fighters. It is sometimes dubbed the "Jihad drug" because of this. It quickly produces a euphoric intensity in users, allowing users to stay awake for very long periods of time. Along with this, one remains more calm and focused under the effects of the drug, which allows for ones senses to stay at more operational levels. It also helps to subdue feelings of fear and hunger, which is beneficial to conducting long term operations. Psychiatrist Dr. Robert Keisling says that it "gives you a sense of well-being and euphoria," along with the thought that "you’re invincible and that nothing can harm you.” Those who go on jihad missions take a lot of it to prepare, says a former fighter associated with the Muslim Brotherhood. He described the effect: "They go blank. Their heart rate spikes. They lose all connection to their emotions and thoughts." Some commented on this effect as a "zombielike detachment."

An illegal Syrian manufactuer told New York Magazine in 2015 of the effect the drug had on fighters: "[If] someone takes many pills, like 30 or so, they become violent and crazy, paranoid, unafraid of anything...They'll have a thirst for fighting and killing and will shoot at whatever they see. They lose any feeling or empathy for the people in front of them and can kill them without caring at all."

According to some commentators, fighters taking the drug in Syria were better able to tolerate the pain of being shot A drug control officer in the central city of Homs told Reuters that protestors and fighters were able to resist painful interrogations better while on Captagon. Former fighters have told the media that the pills helped them overcome their fear. Doctors report that the drug has dangerous side effects, including psychosis and brain damage. According to former fighters, hundreds became addicted to the pills they were given by brigade leaders without knowing what they were taking.

Captagon use was associated with the rise of ISIS. One 19-year-old fighter named Kareem, who said he fought alongside ISIS for more than a year, told CNN in 2014: “They gave us drugs, hallucinogenic pills that would make you go to battle not caring if you live or die.”

In February 2023, Israel’s Ministry of Defense thwarted an attempt to smuggle thousands of captagon tablets into the Gaza Strip. Hamas claimed on the occasion that it seized 50,000 captagon pills on the border and blamed Israel for attempt to dope Gaza.

Israel has publicly stated that captagon was used during the October 7 attacks, but this has been doubted by some experts. Israeli forces said they had found captagon-containing tablets, powder, and liquid on the bodies of the attackers. But Caroline Rose of Newline Institute, said that she had never seen captagon made in liquid form. While precursor chemicals for captagon tend to be in powdered form, captagon itself is not commonly a powder. She concluded "I find it somewhat difficult to believe that, in a single raid, we find two new forms of captagon.” Videos compiled by the Israeli government of the Hamas attack — cobbled together from cell phones, GoPros, as well as car and surveillance cameras — supposedly show that at least some of the militants were under the influence of the drug. Some experts noted Israel had not made public direct evidence of captagon use.

Captagon was used by the ISIS attackers in the Crocus City Hall attack in 2024.

Reaction sequence


Theophylline (1) is alkylated using 2-bromochloroethane (2) in a substitution reaction to give 7-(2-Chloroethyl)theophylline (aka Benaphyllin, Eupnophile) (3). 7-(2-Chloroethyl)theophylline forms a three-carbon ring substructure by displacing the remaining halogen leaving group in an intramolecular substitution reaction. The three-carbon ring substructure is deformed by the primary amine in amphetamine (4), giving fenethylline (5).

Reaction conditions
Theophylline (1) is allowed to react with 2-bromochloroethane (2) by refluxing both compounds at 90 °C for 18h. The produced 7-(2-Chloroethyl)theophylline (3) is filtered and purified. After purification, compound 3 is mixed with amphetamine (4) in a mixture at 100 °C for 17 hours to produce fenethylline (5).

Compound identification
Since fenethylline is a highly controlled drug, a variety of identification methods are needed in order to regulate it. Many identification methods with different samples have been tested. Gas chromatography-mass spectrometry (GC-MS) has been proven as an accurate tool to identify fenethylline in solid samples, as well as in urine and hair samples.