Amphetamine sure, but captagon is a more complicated molecule without any real extra benefit. Théophyllines are meh unless you’re nearly dying of lung disease.

However, Wikipedia reports:

“ Many of these counterfeit "Captagon" tablets actually contain other amphetamine derivatives that are easier to produce, but are pressed and stamped to look like Captagon pills.”

which makes a lot more sense if the chemistry is being done in Syria.