acefylline acefylline acefylline (inn), 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 diphenhydramine induced drowsiness. acefyllineclinical dataatc coder03da09 (who) (acefylline piperazine)identifiers iupac name (1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydro-7h-purin-7-yl)acetic acid cas number652-37-9 npubchem cid69550chemspider62754 yuniim494ue2yepchemblchembl70246 ycomptox dashboard (epa)dtxsid6057796 echa infocard100.010.447 chemical and physical dataformulac9h10n4o4molar mass238.203 g·mol−13d model (jsmol)interactive image smiles o=c2n(c1ncn(c1c(=o)n2c)cc(=o)o)c inchi inchi=1s/c9h10n4o4/c1-11-7-6(8(16)12(2)9(11)17)13(4-10-7)3-5(14)15/h4h,3h2,1-2h3,(h,14,15) ykey:hcyfgrcyscxknq-uhfffaoysa-n y (verify) a silanol–mannuronic acid conjugate of acefylline, acefylline methylsilanol mannuronate (inci; trade name xantalgosil c) is marketed as a lipolytic phosphodiesterase inhibitor. it is used as an ingredient in cosmeceuticals for the treatment of cellulite and as a skin conditioner.