What is "fenethylline"

n. A synthetic prodrug used as a stimulant.

Fenethylline ( BAN, USAN), also spelled phenethylline and fenetylline ( INN), and also known as amphetaminoethyltheophylline and amfetyline, is a codrug of amphetamine and theophylline which behaves as a prodrug to both of the aforementioned drugs. It is marketed for use as a psychostimulant under the brand names Captagon, Biocapton, and Fitton.