etanautine etanautine etanautine, also known as diphenhydramine monoacefyllinate, is an anticholinergic used as an antiparkinsonian agent. it is a 1:1 salt of diphenhydramine with acefylline, similar to the diphenhydramine/8-chlorotheophylline combination product dimenhydrinate. etanautineclinical dataatc coden04ab01 (who) identifiers iupac name 2--n,n-dimethylethanamine; 2-(1,3-dimethyl-2,6-dioxopurin-7-yl)acetic acid cas number857401-00-4 ychemspider8430627unii97h5s09m4tchemical and physical dataformulac26h31n5o5molar mass493.564 g·mol−13d model (jsmol)interactive image smiles o=c2n(c1ncn(c1c(=o)n2c)cc(=o)o)c.o(ccn(c)c)c(c1ccccc1)c2ccccc2 inchi inchi=1s/c17h21no.c9h10n4o4/c1-18(2)13-14-19-17(15-9-5-3-6-10-15)16-11-7-4-8-12-16;1-11-7-6(8(16)12(2)9(11)17)13(4-10-7)3-5(14)15/h3-12,17h,13-14h2,1-2h3;4h,3h2,1-2h3,(h,14,15)key:ufklobybvcbtbp-uhfffaoysa-n (verify) as with dimenhydrinate, the stimulant effect of the etanautine 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.