Overview
11 DESCRIPTION Meclizine hydrochloride, a histamine (H1) receptor antagonist, is a white or slightly yellowish, crystalline powder. It has the following structural formula: Chemically, meclizine hydrochloride is 1-(p-chloro-α-phenylbenzyl)-4-(m-methylbenzyl) piperazine dihydrochloride monohydrate.
Mechanism of Action
12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action The precise mechanism by which meclizine exerts its therapeutic effect is unknown but is presumed to involve antagonism of the histamine H1 receptor. 12.2 Pharmacodynamics There are no relevant pharmacodynamic data regarding meclizine. 12.3 Pharmacokinetics The available pharmacokinetic information for meclizine following oral administration has been summarized from published literature. Absorption Meclizine is absorbed after oral administration with maximum plasma concentrations reaching at a median T max value of 3 hours post-dose (range: 1.5 to 6 hours) for the tablet dosage form. Distribution Drug distribution characteristics for meclizine in humans are unknown.
Indications
- 1 INDICATIONS AND USAGE 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.
Common Doses
- 25 mg
- 100 mg
Dosage
2 DOSAGE AND ADMINISTRATION Recommended dosage: 25 mg to 100 mg daily, in divided doses ( 2.1 ). Tablets: Swallow whole ( 2.2 ). Chewable Tablets: Must be chewed or crushed before swallowing; do not swallow whole ( 2.2 ). 2.1 Recommended Dosage The recommended dosage is 25 mg to 100 mg daily administered orally, in divided doses, depending upon clinical response. 2.2 Administration Instructions Tablets Meclizine hydrochloride tablets must be swallowed whole. Chewable Tablets Meclizine hydrochloride chewable tablets must be chewed or crushed completely before swallowing.
Contraindications
- 4 CONTRAINDICATIONS 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.
Side Effects
- 6 ADVERSE REACTIONS 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.
Interactions
- 7 DRUG INTERACTIONS 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.