Meclizine hydrochloride, an oral antiemetic, is a white, slightly yellowish, crystalline powder which has a slight odor and is tasteless. It has the following structural formula:
C H CIN •2HCI•H O M.W. 481.89
The chemical name is 1-( -chloro-alpha-phenylbenzyl)-4-( -methyl-benzyl) - piperazine dihydrochloride monohydrate.
Meclizine Hydrochloride Tablets are available in 12.5 mg, and *25 mg strengths for oral administration.
*Contains FD&C Yellow #5 (see PRECAUTIONS).
Each tablet contains the following inactive ingredients: colloidal silicon dioxide, lactose, magnesium stearate, microcrystalline cellulose, sodium starch glycolate, starch, and stearic acid. In addition, the 12.5 mg tablet contains FD&C Blue #1; and the 25 mg tablet contains D&C Yellow #10 and FD&C Yellow #5.
Meclizine hydrochloride is an antihistamine which shows marked protective activity against nebulized histamine and lethal doses of intravenously injected histamine in guinea pigs. It has a marked effect in blocking the vasodepressor response to histamine, but only a slight blocking action against acetylcholine. Its activity is relatively weak in inhibiting the spasmogenic action of histamine on isolated guinea pig ileum.
INDICATIONS AND USAGE
For the prevention and treatment of nausea, vomiting, or dizziness associated with motion sickness.
Meclizine hydrochloride is contraindicated in individuals who have shown a previous hypersensitivity to it.
Since drowsiness may, on occasion, occur with use of this drug, patients should be warned of this possibility and cautioned against driving a car or operating dangerous machinery.
Patients should avoid alcoholic beverages while taking the drug. Due to its potential anticholinergic action, this drug should be used with caution in patients with asthma, glaucoma, or enlargement of the prostate gland. Do not give to children under 12 years of age unless directed by a doctor.
The Meclizine Hydrochloride Tablets, 25 mg contain FD&C Yellow #5 (tartrazine) which may cause allergic-type reactions (including bronchial asthma) in certain susceptible individuals. Although the overall incidence of FD&C Yellow #5 (tartrazine) sensitivity in the general population is low, it is frequently seen in patients who also have aspirin hypersensitivity.
Clinical studies establishing safety and effectiveness in children have not been done; therefore, usage is not recommended under 12 years of age.
Usage in Children:
Reproduction studies in rats have shown cleft palates at 25-50 times the human dose. Epidemiological studies in pregnant women, however, do not indicate that meclizine hydrochloride increases the risk of abnormalities when administered during pregnancy.
Usage in Pregnancy:Pregnancy Category B.
Despite the animal findings, it would appear that the possibility of fetal harm is remote. Nevertheless, meclizine hydrochloride, or any other medication should be used during pregnancy only if clearly necessary.
Drowsiness, dry mouth, and on rare occasions, blurred vision have been reported.
DOSAGE AND ADMINISTRATION
The initial dose of 25 to 50 mg meclizine hydrochloride, should be taken one hour prior to travel for protection against motion sickness. Thereafter, the dose may be repeated every 24 hours for the duration of the journey.
MECLIZINE HYDROCHLORIDE (MECLIZINE HYDROCHLORIDE) TABLET