Meclizine

Pronunciation

(MEK li zeen)

U.S. Brand Names

Antivert®; Bonine® [OTC]; Dramamine® Less Drowsy Formula [OTC]

Synonyms

Meclizine Hydrochloride; Meclozine Hydrochloride

Generic Available

Yes

Canadian Brand Names

Antivert®; Bonamine™; Bonine®

Use

Prevention and treatment of symptoms of motion sickness; management of vertigo with diseases affecting the vestibular system

Pregnancy Risk Factor

Pregnancy Implications

No data available on crossing the placenta. Probably no effect on the fetus (insufficient data). Available evidence suggests safe use during pregnancy.

Lactation

Excretion in breast milk unknown/not recommended

Contraindications

Hypersensitivity to meclizine or any component of the formulation

Warnings/Precautions

Use with caution in patients with angle-closure glaucoma, prostatic hyperplasia, pyloric or duodenal obstruction, or bladder neck obstruction; use with caution in hot weather, and during exercise; elderly may be at risk for anticholinergic side effects such as glaucoma, prostatic hyperplasia, constipation, gastrointestinal obstructive disease; if vertigo does not respond in 1-2 weeks, it is advised to discontinue use

Adverse Reactions

>10%:

Central nervous system: Slight to moderate drowsiness

Respiratory: Thickening of bronchial secretions

1% to 10%:

Central nervous system: Headache, fatigue, nervousness, dizziness

Gastrointestinal: Appetite increase, weight gain, nausea, diarrhea, abdominal pain, xerostomia

Neuromuscular & skeletal: Arthralgia

Respiratory: Pharyngitis

<1%: Palpitations, hypotension, depression, sedation, photosensitivity, rash, angioedema, urinary retention, hepatitis, myalgia, tremor, paresthesia, blurred vision, bronchospasm, epistaxis

Overdosage/Toxicology

Symptoms of overdose include CNS depression, confusion, nervousness, hallucinations, dizziness, blurred vision, nausea, vomiting, and hyperthermia. There is no specific treatment for antihistamine overdose. Clinical toxicity is due to blockade of cholinergic receptors. For anticholinergic overdose with severe life-threatening symptoms, physostigmine 1-2 mg I.V. slowly, may be given to reverse these effects.

Drug Interactions

Increased toxicity: CNS depressants, neuroleptics, anticholinergics

Ethanol/Nutrition/Herb Interactions

Ethanol: Avoid ethanol (may increase CNS depression).

Mechanism of Action

Has central anticholinergic action by blocking chemoreceptor trigger zone; decreases excitability of the middle ear labyrinth and blocks conduction in the middle ear vestibular-cerebellar pathways

Pharmacodynamics/Kinetics

Onset of action: ~1 hour

Duration: 8-24 hours

Metabolism: Hepatic

Half-life elimination: 6 hours

Excretion: Urine (as metabolites); feces (as unchanged drug)

Dosage

Children >12 years and Adults: Oral:

Motion sickness: 12.5-25 mg 1 hour before travel, repeat dose every 12-24 hours if needed; doses up to 50 mg may be needed

Vertigo: 25-100 mg/day in divided doses

Patient Education

Take exactly as prescribed; do not increase dose. Avoid alcohol, other CNS depressants, sleeping aids without consulting prescriber. You may experience dizziness, drowsiness, or blurred vision (use caution when driving or engaging in tasks that require alertness until response to drug is known); dry mouth (frequent mouth care, sucking lozenges, or chewing gum may help); constipation (increased exercise, fluids, fruit, or may help); or heat intolerance (avoid excessive exercise, hot environments, maintain adequate hydration). Report CNS change (hallucination, confusion, nervousness); sudden or unusual weight gain; unresolved nausea or diarrhea; chest pain or palpitations; muscle pain; or changes in urinary pattern. Breast-feeding precaution: Breast-feeding is not recommended.

Dental Health: Effects on Dental Treatment

Key adverse event(s) related to dental treatment: Slight to moderate drowsiness, thickening of bronchial secretions, significant xerostomia (normal salivary flow resumes upon discontinuation).

Dental Health: Vasoconstrictor/Local Anesthetic Precautions

No information available to require special precautions

Mental Health: Effects on Mental Status

Drowsiness is common; may cause dizziness or nervousness; may rarely cause sedation or depression

Mental Health: Effects on Psychiatric Treatment

Concurrent use with psychotropic may produce additive sedation and dry mouth

Dosage Forms

Tablet, as hydrochloride: 12.5 mg, 25 mg

Antivert®: 12.5 mg, 25 mg, 50 mg

Dramamine® Less Drowsy Formula: 25 mg

Tablet, chewable, as hydrochloride (Bonine®): 25 mg

References

Oosterveld WJ, "Vertigo: Current Concepts in Management," Drugs , 1985, 30(3):275-83.

Park J, Logan R, and Pottage A, "Drug-Induced Extrapyramidal Signs in Chronic Liver Disease - A Case Report," Clin Toxicol , 1977, 11(1):117-20.

International Brand Names

Antivert® (CA); Bonamine™ (CA); Bonine® (CA)

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