Meclizine

BRAND NAMES

• U.S.: Antivert PI

• Other:
  • Postafen, Postafene, Sea-Legs
  • Itinerol B6 (in combination with Vitamin B6)

STRUCTURE

MECHANISM OF ACTION

Meclizine is an histamine antagonist at H₁ receptors, of the piperazine side chain group; it acts also on CNS by blocking muscarinic receptors (anticholinergic) in the brain.

INDICATIONS

• Management of nausea and vomiting, and dizziness associated with motion sickness.
• Meclizine is also prescribed as an anti-emetic, effective in the management of nausea, vomiting, and dizziness during pregnancy
• Management of vertigo associated with diseases affecting the vestibular system.

DOSAGE

• Vertigo: For the control of vertigo associated with diseases affecting the vestibular system, the recommended dose is 25 to 100 mg daily, in divided dosage, depending upon clinical response.

• Motion Sickness: The initial dose is 25 to 50 mg and should be taken one hour prior to embarkation for protection against motion sickness. Thereafter, the dose may be repeated every 24 hours for the duration of the journey.

• The usual dose for nausea and vomiting during pregnancy is 50 mg at night followed by 25 mg in the morning if necessary.

CONTRAINDICATIONS

• Hypersensitivity to Meclizine

WARNINGS AND PRECAUTIONS

Since drowsiness may, on occasion, occur with use of this drug, patients should be warned of this possibility and cautioned against driving a car or operating dangerous machinery.

Patients should avoid alcoholic beverages while taking this drug.

Due to its potential anticholinergic action, this drug should be used with caution in patients with asthma, glaucoma, or enlargement of the prostate gland.

INTERACTIONS

There may be increased CNS depression when meclizine is administered concurrently with other CNS depressants, including alcohol, tranquilizers, and sedatives.

Based on in-vitro evaluation, meclizine is metabolized by CYP2D6. Therefore there is a possibility for a drug interaction between meclizine and CYP2D6 inhibitors.

PREGNANCY AND LACTATION

• Pregnancy Category B (US). Meclizine should be used during pregnancy only if clearly necessary.

• Nursing mothers: It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when meclizine is administered to a nursing woman.

SIDE EFFECTS

Anaphylactoid reaction, drowsiness, dry mouth, headache, fatigue, vomiting and, on rare occasions, blurred vision have been reported.