Clemastine Syrup

Generic name: clemastine fumarate
Dosage form: syrup
Drug class:Antihistamines

Medically reviewed by Drugs.com. Last updated on Nov 1, 2021.

Clemastine Syrup Description

Each teaspoonful (5 mL) of Clemastine Fumarate Syrup for oral administration contains clemastine 0.5 mg (present as clemastine fumarate 0.67 mg). Other ingredients: alcohol 5.5%, flavor, fumaric acid, methylparaben, propylene glycol, propylparaben, purified water, saccharin sodium, sorbitol in a buffered solution. Clemastine fumarate belongs to the benzhydryl ether group of antihistaminic compounds. The chemical name is (+)-(2R)-2-[2-[[(R)-p-Chloro-α-methyl-α-phenylbenzyl]- oxy]ethyl]-1-methylpyrrolidine fumarate and has the following structural formula:

C21H26CINO.C4H4O4 M.W. 459.97

CAS Registration Number 145976-57-9

Clemastine fumarate occurs as a colorless to faintly yellow, practically odorless, crystalline powder. Clemastine Fumarate Syrup has an approximate pH of 6.2.

Clemastine Syrup - Clinical Pharmacology

Clemastine fumarate is an antihistamine with anticholinergic (drying) and sedative side effects. Antihistamines competitively antagonize various physiological effects of histamine including increased capillary permeability and dilatation, the formation of edema, the "flare" and "itch" response, and gastrointestinal and respiratory smooth muscle constriction. Within the vascular tree, H1-receptor antagonists inhibit both the vasoconstrictor and vasodilator effects of histamine. Depending on the dose, H1- receptor antagonists can produce CNS stimulation or depression. Most antihistamines exhibit central and/or peripheral anticholinergic activity. Antihistamines act by competitively blocking H1-receptor sites. Antihistamines do not pharmacologically antagonize or chemically inactivate histamine, nor do they prevent the release of histamine.

PHARMACOKINETICS

Antihistamines are well-absorbed following oral administration. Chlorpheniramine maleate, clemastine fumarate, and diphenhydramine hydrochloride achieve peak blood levels within 2-5 hours fo...