thiazinamium metilsulfate thiazinamium metilsulfate thiazinamium metilsulfate (inn) or thiazinam is an antihistamine. the usan is thiazinamium chloride (with a different counterion). thiazinamium metilsulfatethiazinamiumclinical dataatc coder06ad06 (who) identifiers iupac name n,n,n-trimethyl-1-(10h-phenothiazin-10-yl)propan-2-aminium cas number58-34-4 ythiazinamium: 2338-21-8 ypubchem cid6015chemspider5793uniiia16wbx317thiazinamium: 666w2p28n2 yecha infocard100.017.320 chemical and physical dataformulac18h23n2s+molar mass299.46 g·mol−13d model (jsmol)interactive image smiles cc(cn1c2=cc=cc=c2sc3=cc=cc=c31)(c)(c)c inchi inchi=1s/c18h23n2s.ch4o4s/c1-14(20(2,3)4)13-19-15-9-5-7-11-17(15)21-18-12-8-6-10-16(18)19;1-5-6(2,3)4/h5-12,14h,13h2,1-4h3;1h3,(h,2,3,4)/q+1;/p-1key:bvidqavccrufgu-uhfffaoysa-m ny (what is this?) (verify) synthesis since many of the uses of antihistamines involve conditions such as rashes, which should be treatable by local application, there is some rationale for developing drugs for topical use. the known side effects of antihistamines could in principle be avoided if the drug were functionalized to avoid systemic absorption. the known poor absorption of quat salts make such derivatives attractive for nonabsorbable antihistamines for topical use. thiazinamium chloride synthesis thus, reaction of the well-known antihistaminic drug promethazine with methylchloride leads to thiazinamium chloride.