MECLIZINE HYDROCHLORIDE — meclizine hydrochloride tablet
Wilshire Pharmaceuticals Inc
Meclizine hydrochloride tablets are indicated for the treatment of vertigo associated with diseases affecting the vestibular system in adults.
The recommended dosage is 25 mg to 100 mg daily administered orally, in divided doses, depending upon clinical response.
Meclizine hydrochloride tablets must be swallowed whole.
- 12.5 mg: Pink mottled, round shaped, biconvex tablets, debossed with ‘I50’ on one side and plain on other side.
- 25 mg: Pink mottled, round shaped, biconvex tablets, debossed with ‘I60’ on one side and plain on other side.
- 50 mg: Pink mottled, oval shaped, biconvex tablets, debossed with ‘I171’ on one side and partial breakline on other side.
Since drowsiness may occur with use of meclizine hydrochloride tablets, patients should be warned of this possibility and cautioned against driving a car or operating dangerous machinery.
Patients should avoid alcoholic beverages while taking meclizine hydrochloride tablets [see Drug Interactions (7.1)].
Because of its potential anticholinergic action, meclizine hydrochloride tablets should be used with caution in patients with asthma, glaucoma, or enlargement of the prostate gland.
The following adverse reactions associated with the use of meclizine hydrochloride tablets were identified in clinical studies or postmarketing reports. Because some of these reactions were reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
Anaphylactic reaction, drowsiness, dry mouth, headache, fatigue, and vomiting. On rare occasions blurred vision has been reported.
There may be increased CNS depression when meclizine hydrochloride tablets are administered concurrently with other CNS depressants, including alcohol [see Warnings and Precautions (5.1)].
Based on in-vitro evaluation, meclizine is metabolized by CYP2D6. Therefore, there is a possibility for a drug interaction between meclizine hydrochloride tablets and CYP2D6 inhibitors. Therefore, monitor for adverse reactions and clinical effect accordingly.
Data from epidemiological studies have not generally indicated a drug-associated risk of major birth defects with meclizine during pregnancy. However, in a published study, an increased incidence of fetal malformations was observed following oral administration of meclizine to pregnant rats during the period of organogenesis, at doses similar to those used clinically.
In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively. The background risk of major birth defects and miscarriage for the indicated population is unknown.
Epidemiological studies reporting on pregnancies exposed to meclizine have not identified an association between the use of meclizine during pregnancy and an increased risk of major birth defects.
In a published study, oral administration of meclizine (25-250 mg/kg) to pregnant rats during the period of organogenesis resulted in a high incidence of fetal malformations. These effects occurred at doses as low as 25 mg/kg, which is approximately 2 times the maximum recommended human dose (100 mg) on a body surface area (mg/m2) basis.
There are no data on the presence of meclizine in human milk, the effects on the breastfed infant, or the effects on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for meclizine hydrochloride tablets and any potential adverse effects on the breastfed infant from meclizine hydrochloride tablets or from the underlying maternal condition.
Safety and effectiveness in pediatric patients have not been established.
In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.
The effect of hepatic impairment on the pharmacokinetics of meclizine has not been evaluated. As meclizine hydrochloride tablets undergo metabolism, hepatic impairment may result in increased systemic exposure of meclizine. Treatment with meclizine hydrochloride tablets should be administered with caution in patients with hepatic impairment.
The effect of renal impairment on the pharmacokinetics of meclizine has not been evaluated. Because of a potential for drug/metabolite accumulation, meclizine hydrochloride tablets should be administered with caution in patients with renal impairment and in the elderly, as renal function generally declines with age.
The genetic polymorphism of CYP2D6 that results in poor-, intermediate-, extensive-, and ultrarapid metabolizer phenotypes could contribute to large inter-individual variability in meclizine exposure. Therefore, when meclizine hydrochloride tablets are administered to patients with CYP2D6 polymorphism, monitor for adverse reactions and clinical effect accordingly.
Meclizine hydrochloride tablets, a histamine (H1) receptor antagonist, are a white or slightly yellowish, crystalline powder. They have the following structural formula:
Chemically, meclizine hydrochloride tablets are 1-(p-chloro-α-phenylbenzyl)-4-(m-methylbenzyl) piperazine dihydrochloride monohydrate.
Inactive ingredients for the tablets are: colloidal silicon dioxide; lactose monohydrate; magnesium stearate; microcrystalline cellulose; sodium starch glycolate; corn starch; FD&C Red # 40.
Each meclizine hydrochloride 12.5 mg tablet contains 12.5 mg of meclizine dihydrochloride equivalent to10.53 mg of meclizine free base.
Each meclizine hydrochloride 25 mg tablet contains 25 mg of meclizine dihydrochloride equivalent to 21.07 mg of meclizine free base.
Each meclizine hydrochloride 50 mg tablet contains 50 mg of meclizine dihydrochloride equivalent to 42.14 mg of meclizine free base.
The precise mechanism by which meclizine exerts its therapeutic effect is unknown but is presumed to involve antagonism of the histamine H1 receptor.
There are no relevant pharmacodynamic data regarding meclizine.
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