Meclizine Hydrocloride

Meclizine hydrochloride is indicated for the treatment of vertigo associated with diseases affecting the vestibular system in adults. Meclizine hydrochloride is indicated for the treatment of vertigo associated with diseases affecting the vestibular system in adults ( 1 ).

Meclizine hydrochloride tablets USP, 12.5 mg (Blue, oval shaped tablets, debossed with “TL 122” with score on one side and plain on the other side.) Meclizine hydrochloride tablets USP, 25 mg (Yellow, oval shaped tablets, debossed with “TL 121” with score on one side and plain on the other side.) Tablets: 12.5 mg, and 25 mg ( 3 ).

Meclizine hydrochloride is contraindicated in patients with a hypersensitivity to meclizine or any of the inactive ingredients [see Adverse Reactions (6) and Description (11) ]. Meclizine hydrochloride is contraindicated in patients with hypersensitivity to meclizine or any of the inactive ingredients ( 4 ).

May cause drowsiness: Use caution when driving a car or operating dangerous machinery ( 5.1 ). Potential anticholinergic action: this drug should be prescribed with care to patients with a history of asthma, glaucoma, or enlargement of the prostate gland ( 5.2 ).

5.1 Drowsiness Since drowsiness may occur with use of meclizine hydrochloride, 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 [see Drug Interactions (7.1) ].

5.2 Concurrent Medical Conditions Because of its potential anticholinergic action, meclizine hydrochloride 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 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. Common adverse reactions are anaphylactic reaction, drowsiness, dry mouth, headache, fatigue, and vomiting. On rare occasions blurred vision has been reported ( 6 ). To report SUSPECTED ADVERSE REACTIONS, contact Jubilant Cadista Pharmaceuticals Inc. at 1-800­313-4623 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

Coadministration of Meclizine hydrochloride with other CNS depressants, including alcohol, may result in increased CNS depression ( 7.1 ). CYP2D6 inhibitors: As meclizine is metabolized by CYP2D6, there is a potential for drug-drug interactions between Meclizine hydrochloride and CYP2D6 inhibitors ( 7.2 ). 7.1 CNS Depressants There may be increased CNS depression when meclizine hydrochloride is administered concurrently with other CNS depressants, including alcohol [see Warnings and Precautions (5.1) ]. 7.2 CYP2D6 Inhibitors Based on in-vitro evaluation, meclizine is metabolized by CYP2D6. Therefore, there is a possibility for a drug interaction between meclizine hydrochloride and CYP2D6 inhibitors. Therefore, monitor for adverse reactions and clinical effect accordingly.

8.1 Pregnancy Risk Summary 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 to 4% and 15 to 20%, respectively. The background risk of major birth defects and miscarriage for the indicated population is unknown. Data Human Data 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. Animal Data 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/m 2 ) basis.

8.2 Lactation Risk Summary 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 and any potential adverse effects on the breastfed infant from Meclizine hydrochloride or from the underlying maternal condition.

8.4 Pediatric Use Safety and effectiveness in pediatric patients have not been established.

8.5 Geriatric Use 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.

8.6 Hepatic Impairment The effect of hepatic impairment on the pharmacokinetics of meclizine has not been evaluated. As meclizine hydrochloride undergoes metabolism, hepatic impairment may result in increased systemic exposure of meclizine. Treatment with meclizine hydrochloride should be administered with caution in patients with hepatic impairment.

8.7 Renal 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 should be administered with caution in patients with renal impairment and in the elderly, as renal function generally declines with age.

8.8 Genetic CYP2D6 Polymorphism 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 is administered to patients with CYP2D6 polymorphism, monitor for adverse reactions and clinical effect accordingly.

The precise mechanism by which meclizine exerts its therapeutic effect is unknown but is presumed to involve antagonism of the histamine H1 receptor.