8-Chlorotheophylline, also known as 1,3-dimethyl-8-chloroxanthine, is a stimulantdrug of the xanthine chemical class, with physiological effects similar to caffeine.[1] Its main use is in combination (salt) with diphenhydramine in the antiemeticdimenhydrinate (Dramamine). Diphenhydramine reduces nausea but causes drowsiness, and the stimulant properties of 8-Chlorotheophylline help reduce that side effect.[2]
Despite being classified as a xanthine stimulant, 8-chlorotheophylline can generally not produce any locomotor activity above control in mice and does not appear to cross the blood-brain barrier well.[citation needed]
The 8-chloro modification is not selected for pharmacological properties; instead, it was to raise the acidity of the xanthine amine group enough to form a co-salt with diphenhydramine.[2]
The drug is also sold in combination with promethazine, again as a salt.[3]
^https://www.ebi.ac.uk/chebi/searchId.do?chebiId=8461 "The anti-emetic action of both the hydrochloride and the teoclate (8-chlorotheophylline) salts is used for the prevention of nausea in cases of motion sickness and post-operative vomiting."