Originator
Tavegyl,Sandoz,France,1967
Uses
Clemastine is used for allergy symptoms, rhinites, Quinke’s edema, anaphylactic shock,
hay fever, allergic dermatitis and dermatosis, and chronic eczema. Synonyms of this drug
are tavegil and meclastine.
Definition
ChEBI: 2-[(2R)-1-Methylpyrrolidin-2-yl]ethanol in which the hydrogen of the hydroxy group is substituted by a 1-(4-chlorophenyl)-1-phenylethyl group (R configuration). An antihistamine with antimuscarinic and moderate sedative pr
perties, it is used as its fumarate salt for the symptomatic relief of allergic conditions such as rhinitis, urticaria, conjunctivitis and in pruritic (severe itching) skin conditions.
Manufacturing Process
9.9 g of α-methyl-p-chlorobenzhydrol are added to a suspension of 2.3 g of
powdered sodamide in 30 cc of benzene. Subsequently 7.4 g of Nmethylpyrrolidyl-(2)-ethyl chloride are added and the solution is heated to the
boil at reflux for 20 hours. Then shaking is first effected with water and then 4
times each time with 25 cc of 2 N hydrochloric acid. The acid extracts are
made alkaline with potassium hydroxide solution while cooling strongly, and
the precipitated oil is extracted with ether. After drying of the ethereal solution
over potassium carbonate, the solvent is evaporated and the residue is
fractionally distilled in a high vacuum, whereby N-methyl-2-[2'-(α-methyl-pchlorobenzhydryloxy)-ethyl]-pyrrolidine boils over at 154°C/0.02 mm Hg. The
base is converted to the fumarate by reaction with fumaric acid.
brand name
Tavist (Novartis);Aller-ez plus;Alogynan;Antihist-1;Arrest;Benaznyl;Clemastin fumerate syrup;Corto-tavegil;Dexa-tavegil;Fumarsutin;Licasol;Maikohist;Mallermin;Rhinergal tavegil;Tavist 1;Tavist tablets;Tavist-1;Tavist-d;Tavist-syrup.
Therapeutic Function
Antihistaminic
Clinical Use
Antihistamine:
Symptomatic relief of allergy such as hay fever,
urticaria
Synthesis
Clemastine, 2-[2-[1-(4-chlorophenyl)-1-phenylethoxy]ethyl]-1-methylpyrrolidine
(16.1.4), is synthesized by reacting 1-(4-chlorophenyl)-1-phenylethanol (16.1.3) with 2-
(2-chlorethyl)-2-methylpyrrolidine using sodium amide as a base. The starting
1-(4-chlorophenyl)-1-phenylethanol (16.1.3) is synthesized either by reacting 4-chlorobenzophenone
with methylmagnesium chloride, or by reacting 4-chloroacetophenone with
phenylmagnesium bromide.
Drug interactions
Potentially hazardous interactions with other drugs
Analgesics: sedative properties increased with opioid
analgesics.
Metabolism
Extensively metabolised in the liver mainly by mono- and
didemethylation and glucuronide conjugation.
The metabolites are mainly excreted in the urine.
