meclizine hydrochloride

meclizine hydrochloride (meclozine (UK))

Antivert, Bonamine (CA), Bonine, Dramamine Less Drowsy Formula, Sea-Legs (UK), Traveleeze (UK)

Pharmacologic class: Anticholinergic

Therapeutic class: Antiemetic, antivertigo drug

Pregnancy risk category B

Action

Decreases excitability of middle-ear labyrinth and depresses conduction in vestibular-cerebellar pathways

Availability

Tablets: 12.5 mg, 25 mg, 50 mg

Tablets (chewable): 25 mg

Indications and dosages

➣ Motion sickness

Adults: 25 to 50 mg P.O. 1 hour before travel. May repeat q 24 hours for duration of travel.

➣ Vertigo associated with diseases affecting the vestibular system

Adults: 25 to 100 mg P.O. daily in divided doses

Contraindications

• Hypersensitivity to drug

Precautions

Use cautiously in:

• prostatic hypertrophy, stenosing peptic ulcer, bladder neck obstruction, pyloroduodenal obstruction, arrhythmias, angle-closure glaucoma, bronchial asthma

• pregnant or breastfeeding patients

• children (younger than age 12).

Administration

• Know that tablets may be chewed or swallowed whole.

Adverse reactions

CNS: drowsiness, fatigue, confusion, excitement, euphoria, nervousness, restlessness, insomnia, vertigo, visual and auditory hallucinations, seizures

CV: hypotension, palpitations, tachycardia

EENT: blurred vision, diplopia, tinnitus, dry nose, dry throat

GI: nausea, vomiting, diarrhea, constipation, dry mouth, anorexia

GU: difficulty urinating, urinary retention, urinary frequency

Skin: rash, urticaria

Interactions

Drug-drug. Anticholinergics (including some antihistamines, antidepressants, atropine, haloperidol, phenothiazines): additive anticholinergic effects

Antihistamines, CNS depressants (such as opioids, sedative-hypnotics): additive CNS depression

Drug-diagnostic tests. Skin tests using allergen extracts: false-negative results

Drug-behaviors. Alcohol use: additive CNS depression

Patient monitoring

• Discontinue drug, as ordered, at least 4 days before skin testing.

• Know that drug has anticholinergic effects.

Patient teaching

• Tell patient to take as prescribed to minimize adverse effects.

• Caution patient to avoid driving and other hazardous activities until he knows how drug affects concentration and alertness.

• Advise patient to relieve dry mouth with hard candy or frequent sips of fluids.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, and behaviors mentioned above.