Etanautine, also known as diphenhydramine monoacefyllinate, is an anticholinergic

Anticholinergic

An anticholinergic agent is a substance that blocks the neurotransmitter acetylcholine in the central and the peripheral nervous system. An example of an anticholinergic is dicycloverine, and the classic example is atropine....

 used as an antiparkinsonian agent. It is a 1:1 salt of diphenhydramine

Diphenhydramine

Diphenhydramine hydrochloride is a first-generation antihistamine possessing anticholinergic, antitussive, antiemetic, and sedative properties which is mainly used to treat allergies. Like most other first-generation antihistamines, the drug also has a powerful hypnotic effect, and for this reason...

 with acefylline

Acefylline

Acefylline, also known as acetyloxytheophylline, is a stimulant drug of the xanthine chemical class. It acts as an adenosine receptor antagonist. It is combined with diphenhydramine in the pharmaceutical preparation etanautine to help offset its sedative effects.- References :...

, similar to the diphenhydramine/8-chlorotheophylline combination product dimenhydrinate

Dimenhydrinate

Dimenhydrinate is an over-the-counter drug used to prevent nausea and motion sickness...

.

As with dimenhydrinate, the stimulant effect of the acefylline counteracts the sedative effect from the diphenhydramine, resulting in an improved therapeutic profile.

The 1:2 salt diphenhydramine diacefylline (with two molecules of acefylline to each molecule of diphenhydramine) is also used in medicine, under the brand name Nautamine.