Flunarizine

Absorption

85% following oral administration.

Toxicity

-Flunarizine should be used with care in patients with depression or those being prescribed other agents, such as phenothiazines, concurrently, which may cause extrapyramidal side-effects. -Acute overdosage has been reported and the observed symptoms were sedation, agitation and tachycardia. -Treatment of acute overdosage consists of charcoal administration, induction of emesis or gastric lavage, and supportive measures. No specific antidote is known.

Description

Flunarizine is the difluorinated derivative of cinnarizine. Thus, its preparation and therapeutic use are identical to those of cinnarizine.

Originator

Sibelium,Janssen,W. Germany,1977

The Uses of Flunarizine

Vasodilator.

Indications

Used in the prophylaxis of migraine, occlusive peripheral vascular disease, vertigo of central and peripheral origin, and as an adjuvant in the therapy of epilepsy.

Background

Flunarizine is a selective calcium entry blocker with calmodulin binding properties and histamine H1 blocking activity. It is effective in the prophylaxis of migraine, occlusive peripheral vascular disease, vertigo of central and peripheral origin, and as an adjuvant in the therapy of epilepsy.

Definition

ChEBI: Flunarizine is a diarylmethane.

Manufacturing Process

A mixture of 14.3 parts of di-(p-fluorophenyl)-chloromethane, 10.1 parts of 1- cinnamylpiperazine, 12.7 parts of sodium carbonate, a few crystals of potassium iodide in 200 parts of 4-methyl-2-pentanone is stirred and refluxed for 21 hours. The reaction mixture is cooled and 50 parts of water are added. The organic layer is separated, dried, filtered and evaporated.
The oily residue is dissolved in 480 parts of anhydrous diisopropyl ether. This solution is boiled with activated charcoal, filtered and to the clear filtrate is added an excess of 2-propanol, previously saturated with gaseous hydrogen chloride. The precipitated salt is filtered off and recrystallized from a mixture of 2-propanol and ethanol, yielding 1-cinnamyl-4-(di-p-fluorobenzhydryl) piperazine dihydrochloride, MP 251.5°C.

Therapeutic Function

Vasodilator

World Health Organization (WHO)

Flunarizine, an antihistaminic and vasodilator agent, was introduced into medicine in 1970. It is indicated for the treatment of central and peripheral vascular disorders. However, its effectiveness in these conditions has not been convincingly demonstrated, and its use has been associated with adverse reactions involving the central nervous system, including extrapyramidal disturbances and depression. This has led several regulatory authorities to restrict the approved indications for products containing flunarizine.

Pharmacokinetics

Flunarizine is a selective calcium entry blocker with calmodulin binding properties and histamine H1 blocking activity.

Metabolism

Hepatic, to two metabolites via N-dealylation and hydroxylation.