CYCLIZINE Chemical Properties

pka

pKa 8.16 (Uncertain)

CYCLIZINE Usage And Synthesis

Originator

Marezine,BurroughsWellcome,US,1953

Uses

Cyclizine is an antihistamine with a sedative effect used in the treatment of nausea and vomiting associated with motion sickness.

Manufacturing Process

One-tenth mol (20 g) of benzhydryl chloride was mixed with 0.19 mol (19 g) of N-methylpiperazine and about 10 cc of benzene and the whole was heated on the steam bath four hours. The contents of the flask was partitioned between ether and water, and the ethereal layer was washed with water until the washings were neutral. The base was then extracted from the ethereal layer by N hydrochloric acid and the extract, made acid to Congo red paper, was evaporated under vacuum. 29.5 g of the pure dihydrochloride of Nmethyl-N'-benzhydryl piperazine was recovered from the residue by recrystallization from 95% alcohol melting above 250°C with decomposition. The addition of alkali to an aqueous solution of the dihydrochloride liberated the base which was recovered by recrystallization from petroleum ether melting at 105.5° to 107.5°C.

Therapeutic Function

Antinauseant

Clinical Use

Nausea and vomiting

Vertigo

Motion sickness

Labyrinthine disorders

Metabolism

Cyclizine is metabolised in the liver to the relatively inactive N-demethylated metabolite, norcyclizine. Both cyclizine and norcyclizine have plasma elimination halflives of 20 hours.
Less than 1% of the total oral dose is eliminated in the urine in 24 hours.