Title: Clemastine
CAS Registry Number: 15686-51-8
CAS Name: (2R)-2-[2-[(1R)-1-(4-Chlorophenyl)-1-phenylethoxy]ethyl]-1-methylpyrrolidine
Additional Names: (+)-2-[2-[(p-chloro-a-methyl-a-phenylbenzyl)oxy]ethyl]-1-methylpyrrolidine; 1-methyl-2-[2-(a-methyl-p-chlorobenzhydryloxy)ethyl]pyrrolidine; 1-methyl-2-[2-(methyl-p-chlorodiphenylmethyloxy)ethyl]pyrrolidine; meclastine
Molecular Formula: C21H26ClNO
Molecular Weight: 343.89
Percent Composition: C 73.34%, H 7.62%, Cl 10.31%, N 4.07%, O 4.65%
Literature References: Prepn: GB 942152 (1963 to Sandoz). Synthesis and abs config: A. Ebnöther, H. P. Weber, Helv. Chim. Acta 59, 2462 (1976). Pharmacology and toxicology of the hydrogen fumarate: Weidmann et al., Boll. Chim. Farm. 106, 467 (1967). HPLC determn in plasma: V. Horváth et al., J. Chromatogr. B 816, 153 (2005).
Properties: Free base, bp0.02 154°. nD22 1.5582. [a]D20 +33.6° (ethanol).
Boiling point: bp0.02 154°
Optical Rotation: [a]D20 +33.6° (ethanol)
Index of refraction: nD22 1.5582
Derivative Type: Hydrogen fumarate
CAS Registry Number: 14976-57-9
Manufacturers' Codes: HS-592
Trademarks: Aloginan (Tobishi); Alphamin (SS Pharm.); Anhistan (Nippon Zoki); Fuluminol (Tatsumi); Inbestan (Maruko); Kinotomin (Toa Eiyo); Lacretin (Tokyo Tanabe); Lecasol (Kaken); Maikohis (Nichiiko); Mallermin-F (Taiyo); Marsthine (Towa Yakuhin); Masletine (Sioe); Piloral (Nippon Kayaku); Reconin (Toyama); Tavegil (Novartis); Tavegyl (Novartis); Tavist (Novartis); Telgin-G (Takeda); Trabest (Hoei); Xolamin (Sanko)
Molecular Formula: C25H30ClNO5
Molecular Weight: 459.96
Percent Composition: C 65.28%, H 6.57%, Cl 7.71%, N 3.05%, O 17.39%
Properties: mp 177-178°. [a]D21 +16.9° (methanol). LD50 in mice, rats (mg/kg): 730, 3550 orally; 43, 82 i.v. (Weimann).
Melting point: mp 177-178°
Optical Rotation: [a]D21 +16.9° (methanol)
Toxicity data: LD50 in mice, rats (mg/kg): 730, 3550 orally; 43, 82 i.v. (Weimann)
Therap-Cat: Antihistaminic.
Keywords: Antihistaminic; Aminoalkylethers.
Clemizole Clenbuterol Clentiazem Clethodim Clevidipine

Clemastine ball-and-stick.png
Systematic (IUPAC) name
Clinical data
Trade names Tavist-1
AHFS/ monograph
MedlinePlus a682542
Pregnancy cat. B (USA)
Legal status Unscheduled;
Routes Oral
Pharmacokinetic data
Bioavailability 39.2%
Metabolism Hepatic
Half-life 21.3 Hours
Excretion Renal
CAS number 15686-51-8 YesY
ATC code D04AA14 R06AA04
PubChem CID 26987
DrugBank DB00283
ChemSpider 25129 YesY
KEGG D03535 YesY
Chemical data
Formula C21H26ClNO 
Mol. mass 343.9
 YesY (what is this?)  (verify)

Clemastine, also known as meclastin, is an antihistamine and anticholinergic. Unlike loratadine or fexofenadine, clemastine is a sedating antihistamine, however it exhibits fewer other side effects than most of the widely used antihistamines.[citation needed] Clemastine is also classified as an antipruritic (i.e. it stops itching).