Home Drug Guide Meclizine Hydrochloride

Drug Guide

Generic Name

Meclizine Hydrochloride

Brand Names Antivert

Classification

Therapeutic: Antiemetic, Motion Sickness Agent

Pharmacological: Antihistamine (H1 antagonist)

FDA Approved Indications

Motion sickness
Vertigo

Mechanism of Action

Meclizine is an H1 histamine receptor antagonist that blunts the vestibular apparatus responses and reduces nausea and vomiting associated with motion sickness and vertigo.

Dosage and Administration

Adult: 25-50 mg, 1 hour before travel, then 25 mg 24 hours later if needed

Pediatric: 6-12 years: 12.5-25 mg 1 hour before travel, then 12.5 mg 24 hours later if needed (consult specific dosing for age and weight)

Geriatric: Typically start at lower end of dosing range due to increased sensitivity

Renal Impairment: Adjust dose based on severity, use with caution

Hepatic Impairment: Use with caution; no specific dose adjustment established

Pharmacokinetics

Absorption: Well absorbed from gastrointestinal tract

Distribution: Widely distributed, crosses the blood-brain barrier

Metabolism: Hepatically metabolized

Excretion: Renal excretion of unchanged drug and metabolites

Half Life: Approximately 6 hours

Contraindications

Hypersensitivity to meclizine or other antihistamines
Pregnancy (category B, use only if clearly needed)

Precautions

Use with caution in patients with glaucoma, urinary retention, or GI obstruction; caution in elderly due to increased sedation and anticholinergic effects

Adverse Reactions - Common

Drowsiness (Very common)
Dry mouth (Common)
Dizziness (Common)

Adverse Reactions - Serious

Severe allergic reactions (rare) (Rare)
Respiratory depression (rare, especially in overdose) (Rare)

Drug-Drug Interactions

Addictive CNS depressants (e.g., alcohol, sedatives)
Other anticholinergic drugs

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor for signs of drowsiness, anticholinergic effects, and effectiveness in controlling vertigo or motion sickness.

Diagnoses:

Risk for injury related to dizziness or drowsiness
Ineffective airway clearance if anticholinergic effects cause dry secretions

Implementation: Administer as directed, usually 1 hour before travel or vertigo episodes. Advise patients to avoid operating heavy machinery.

Evaluation: Assess reduction in vertigo symptoms and tolerance; monitor for adverse effects.

Patient/Family Teaching

Take medication as directed, preferably 1 hour before travel or vertigo episodes.
Caution against driving or operating machinery until response is known.
Report excessive drowsiness, dry mouth, or allergic reactions.
Avoid alcohol and other CNS depressants.

Special Considerations

Black Box Warnings: N/A

Genetic Factors: None specified

Lab Test Interference: None noted

Overdose Management

Signs/Symptoms: Extreme drowsiness, hallucinations, seizures, agitation, hallucinations, dry mouth, urinary retention, hallucinations

Treatment: Supportive care, gastric lavage if recent ingestion, activated charcoal, symptomatic treatment for anticholinergic toxicity.

Storage and Handling

Storage: Store at room temperature, away from moisture and light

Stability: Stable under recommended storage conditions