The detention of a Saudi royal on Monday with over two tonnes of the drug Captagon has put the focus on the popular drug that is widely used by the Islamic State (Isis) terrorists to keep them alert and focused.

Lebanon arrested a Saudi prince along with four others who were attempting to smuggle 40 boxes containing Captagon amphetamine pills and cocaine out of Beirut airport.

The Saudi group was scheduled to fly to Hael in northern Saudi Arabia in their private plane when the excess weight of their luggage raised suspicion.  

Lebanese al-Manar TV channel identified the arrested Saudi royal as prince Abdul Muhsen bin Walid bin Abduld Aziz Al Saud.

Captagon is banned in most countries for being too addictive, but is hugely popular in the Middle East.  Lebanese psychiatrist, Ramzi Haddad told The Guardian that Captagon had "the typical effects of a stimulant", producing "a kind of euphoria. You're talkative, you don't sleep, you don't eat, you're energetic." 

In Syria, militant groups including the Islamic State (Isis) not only consume the drug but also sell it in Gulf countries such as Saudi Arabia; the revenue generated is used for buying weapons.

A Reuters investigation found that due to the breakdown in the law and order situation in the country, Syria today has become a major producer of this easy-to-manufacture drug.

The investigations found that while Saudi Arabia was the largest consumer of the banned drug, Kuwait and the United Arab Emirates were also big consumers.

Colonel Ghassan Chamseddine, head of Lebanon's drug enforcement unit told Times magazine that the sale of amphetamine generated revenues in millions of dollars, some of which was almost certainly used to fund weapons.

"They run two or three operations like that, and they can easily get $300 million. That would buy a lot of guns."