Introduction ⬇
AHFS Class:
Generic Name(s):
Meclizine, a piperazine-derivative antihistamine, is an antiemetic.
Uses ⬆ ⬇
Motion Sickness 
Meclizine hydrochloride is used in the prevention and treatment of nausea, vomiting, and/or vertigo associated with motion sickness. Meclizine is most effective against motion sickness when given prophylactically, although susceptibility to motion sickness may vary with the patient's age, previous exposure to motion, and the type, severity, and duration of motion. Although scopolamine generally is considered to be the most effective drug for the treatment of motion sickness, most clinicians prefer an antihistamine such as meclizine because it produces fewer adverse anticholinergic effects than does scopolamine. Meclizine and dimenhydrinate generally are considered to be equally effective in the treatment of motion sickness, but dimenhydrinate causes drowsiness more frequently. Meclizine has a longer duration of action than scopolamine and most other antihistamines. Promethazine may be more effective than other antihistamines in the treatment of motion sickness.
Other Uses
Meclizine has been used in the symptomatic treatment of vertigo associated with diseases affecting the vestibular system (e.g., labyrinthitis, Ménière's disease), but the value of the drug in these conditions has not been established. Like other antihistamines, meclizine is less effective than the phenothiazines in controlling nausea and vomiting not related to vestibular stimulation.
Although meclizine is a histamine H1-receptor antagonist, its use in allergic states has not been evaluated.
Dosage and Administration ⬆ ⬇
Administration
Meclizine hydrochloride is administered orally.
Dosage
For the prevention and treatment of nausea, vomiting, and/or vertigo associated with motion sickness, the usual oral dosage of meclizine hydrochloride in adults and children 12 years of age or older is 25-50 mg once daily or as directed by a physician.100,101,102,103 For the prevention of motion sickness, 25-50 mg of the drug may be given 1 hour before exposure to motion.101,102
For the control of vertigo associated with diseases affecting the vestibular system, the usual adult dosage is 25-100 mg daily, administered in divided doses.
Cautions ⬆ ⬇
Adverse Effects
Drowsiness, fatigue, dry mouth, and, rarely, blurred vision have occurred after administration of meclizine.
Precautions and Contraindications
Patients should be warned that meclizine may impair their ability to perform hazardous activities requiring mental alertness or physical coordination (e.g., operating machinery, driving a motor vehicle). In addition, additive CNS depression may occur when antihistamines, such as meclizine, are administered concomitantly with other CNS depressants including barbiturates, tranquilizers, and alcohol. If meclizine is used concomitantly with other depressant drugs, caution should be used to avoid overdosage. The anticholinergic effects of the drug should be considered when administering meclizine to patients with angle-closure glaucoma or prostatic hypertrophy.
Meclizine is contraindicated in patients who are hypersensitive to it.
Pediatric Precautions
Safety and efficacy of meclizine in children younger than 12 years of age have not been established; therefore, the manufacturers state that use of the drug in this age group is not recommended. If the drug is used in this age group (e.g., for the prevention and treatment of nausea, vomiting, and/or vertigo associated with motion sickness), it should be only under the advice and supervision of a physician.100
Pregnancy
Pregnancy
Meclizine is teratogenic in animals. Although retrospective studies in humans suggest that the use of meclizine during pregnancy is probably not associated with teratogenic effects, the manufacturers state that the drug is contraindicated in women who are or may become pregnant.
Other Information ⬆ ⬇
Pharmacology
Meclizine has CNS depressant, anticholinergic, antiemetic, antispasmodic, and local anesthetic effects in addition to antihistaminic activity. The drug depresses labyrinth excitability and conduction in vestibular-cerebellar pathways. The antiemetic and antimotion-sickness actions of meclizine result, at least in part, from its central anticholinergic and CNS depressant properties.
Pharmacokinetics
The onset of action of meclizine hydrochloride is about 1 hour and the drug has a prolonged duration of action, with effects persisting 8-24 hours following administration of a single oral dose. The drug has a plasma half-life of 6 hours. The metabolic fate of meclizine in humans is unknown. In rats, meclizine is metabolized (probably in the liver) to norchlorcyclizine. This metabolite is distributed throughout most body tissues and crosses the placenta. The drug is excreted in feces unchanged and in urine as norchlorcyclizine.
Chemistry and Stability
Chemistry
Meclizine is a piperazine-derivative antihistamine that is used as an antiemetic. Meclizine hydrochloride occurs as a white or slightly yellowish, crystalline powder, has a slight odor and is tasteless, and is practically insoluble in water and slightly soluble in alcohol.
Stability
Meclizine hydrochloride preparations should be stored at a temperature less than 40°C, preferably between 15-30°C; the conventional tablets should be stored in well-closed containers.
Additional Information
The American Society of Health-System Pharmacists, Inc. represents that the information provided in the accompanying monograph was formulated with a reasonable standard of care, and in conformity with professional standards in the field. Readers are advised that decisions regarding use of drugs are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and that the information contained in the monograph is provided for informational purposes only. The manufacturer's labeling should be consulted for more detailed information. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information contained in the monograph is not a substitute for medical care.
Preparations ⬆ ⬇
Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.
Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.
Meclizine Hydrochloride
* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name
Copyright ⬆ ⬇
AHFS® Drug Information. © Copyright, 1959-2024, Selected Revisions October 10, 2024. American Society of Health-System Pharmacists, Inc., 4500 East-West Highway, Suite 900, Bethesda, MD 20814.
References ⬆
100. Food and Drug Administration. Antiemetic drug products for over-the-counter human use; final monograph. Fed Regist . 1987; 52:15886-93.
101. Leeming Division. Bonine® (meclizine hydrochloride) chewable tablets prescribing information. In: Huff BB, ed. Physicians' desk reference for nonprescription drugs. 9th ed. Oradell, NJ: Medical Economics Company Inc; 1988:569.
102. Roerig. Antivert® tablets, Antivert®25 tablets, Antivert®25 chewable tablets, and Antivert®50 tablets prescribing information. In: Huff BB, ed. Physicians' desk reference. 43rd ed. Oradell, NJ: Medical Economics Company Inc; 1989:1774.
103. Food and Drug Administration. Over-the-counter drug products; final monographs for antiemetic, antitussive, bronchodilator, and antihelmintic drug products; updating and technical changes. Fed Regist . 1988; 53:35808-10.