Bonamine™
Meclizine HCl
Antiemetic
Pfizer Consumer Healthcare
http://www.pfizer.com/pfizer/main.jsp
Bonamine Monograph PDF download here.
CPS:PIS_m095000
Pharmacology
Meclizine has antihistaminic and anticholinergic
properties. The site and mechanism of action of meclizine in controlling
vertigo arising from various conditions, have not been clearly defined.
Pharmacological studies conducted with other antihistamines show that the
peripheral labyrinthine structures may be the site of action.
Indications
For prophylaxis and symptomatic relief of
nausea, vomiting and vertigo associated with motion sickness, radiation
sickness, Ménière's syndrome, labyrinthitis and other vestibular disturbances.
Contraindications
In patients with known hypersensitivity to
meclizine.
Warnings
Occupational Hazards
Patients should be warned that meclizine may
occasionally cause drowsiness and that when taking it they should take the
necessary precautions against driving or operating dangerous machinery.
Patients suffering from
glaucoma, prostatic enlargement, asthma, chronic lung disease, emphysema,
pregnant, or breast-feeding should take meclizine only under the direction of a
physician. Avoid alcohol.
As with all antihistamines,
meclizine may cause hyperexcitability in children.
Precautions
Pregnancy
Epidemiological studies with meclizine in women
experiencing nausea and vomiting of pregnancy has revealed no evidence of a
teratogenic effect attributable to the drug.
As with many other
drugs of this class, certain teratogenic effects have been observed in the rat.
In the rat meclizine at doses of 25 to 50 times the human dose
has shown certain fetal abnormalities. These abnormalities have not been observed
in other experimental animals, including the monkey.
The use of meclizine by
women who are pregnant or may become pregnant requires that the potential
benefits be weighed against the potential risks.
Drug Interactions
There may be increased CNS depression when meclizine
is administered concurrently with other CNS depressants, including
barbiturates, alcohol, tranquilizers and sedatives. Do not take with other
antihistamines.
MAO inhibitors may
prolong and intensify the anticholinergic effects of meclizine.
Adverse Effects
Drowsiness, dry mouth, fatigue, vomiting and, on
rare occasions, blurred vision have been reported with meclizine therapy.
Overdose
For management of a
suspected drug overdose, CPhA recommends that you contact your regional
Poison Control Centre. See the CPS Directory section for a list of
Poison Control Centres.
Symptoms
In adults, the usual signs of meclizine overdose
are CNS depression with drowsiness, coma and convulsions. Hypotension may also
occur, particularly in the elderly. In children, anticholinergic effects and
CNS stimulation (hallucinations, seizures, trouble sleeping) are more likely to
occur.
Treatment
There is no specific antidote for treatment of
meclizine overdosage. Symptomatic and supportive treatment should be employed.
If ingestion is recent (within 1 hour), induce emesis (syrup of ipecac is
recommended; precautions against aspiration are required, especially in infants
and children) or empty stomach by gastric lavage if patient has been unable to
vomit within 3 hours of ingestion. Activated charcoal may also be used.
Keep patient calm to minimize excitation. Vasopressors (norepinephrine or
phenylephrine) may be used to correct hypotension. Physostigmine may be useful
to counteract the CNS anticholinergic effects of meclizine. Do not use
stimulants. If vasopressors are indicated do not use epinephrine, because it
may lower blood pressure further. Diazepam i.v. may be given for treatment of
seizures that do not respond to physostigmine.
Dosage
Adults: The recommended dose for specific
indications is: Motion Sickness: A single dose
of 25 to 50 mg affords protection against motion sickness
for approximately 24 hours. The initial dose should be taken at least
1 hour prior to traveling in order to insure absorption of the drug, as
retention of the medication is uncertain in individuals who have already
developed motion sickness. Thereafter, the dose may be repeated every
24 hours as indicated for the duration of the journey.
Labyrinthine and Vestibular Disturbances: The optimal
dosage is usually 25 to 100 mg daily in divided doses, depending
on the clinical response.
Radiation Sickness: 50 mg administered
2 to 12 hours prior to radiation treatment.
Children
Children require about one half the adult dose.
The fruit-flavored
tablets may be chewed, swallowed whole or allowed to dissolve in the mouth.
Supplied
Each scored, white, fruit-flavored tablet
contains: meclizine HCl 25 mg. Nonmedicinal ingredients: cellulose,
cornstarch, lactose, magnesium stearate/sodium lauryl sulfate, raspberry flavor
and sucrose. Gluten- and tartrazine-free. Bottles of 100. Blister packages
(for OTC use) of 5 and 15 tablets. Store between 15 and 30°C.
