8-Chlorotheophylline
8-Chlorotheophylline is a stimulant drug of the xanthine chemical class, with physiological effects similar to caffeine. Its main use is in combination with [Diphenhydramine] as the antiemetic drug [Dimenhydrinate]. The stimulant properties of 8-chlorotheophylline are thought to ward off the drowsiness caused by diphenhydramine's anti-histamine activity in the central nervous system.   8-chlorotheophylline produces a number of effects including nervousness, restlessness, insomnia, headache, and nausea, which are primarily attributed to its ability to block the adenosine receptor. Because adenosine causes a decrease in neuronal firing, blockade of the adenosine receptor causes the reverse effect resulting in excitation.