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Overview
Clemastine is a antihistamine that is FDA approved for the treatment of allergic rhinitis, urticaria and angioedema. Common adverse reactions include .
Adult Indications and Dosage
FDA-Labeled Indications and Dosage (Adult)
Indications
Clemastine fumarate tablets are indicated for the relief of symptoms associated with allergic rhinitis such as sneezing, rhinorrhea, pruritus, and lacrimation.
Clemastine fumarate tablets are also indicated for the relief of mild, uncomplicated allergic skin manifestations of urticaria and angioedema.
It should be noted that clemastine is indicated for the dermatologic indications at the 2.68 mg dosage level only.
Dosage
DOSAGE SHOULD BE INDIVIDUALIZED ACCORDING TO THE NEEDS AND RESPONSE OF THE PATIENT.
The recommended starting dose is 1.34 mg (1/2 tablet) twice daily. Dosage may be increased as required. Clemastine fumarate tablets are recommended for the dermatologic indications at the 2.68 mg dosage level only.
The maximum recommended dosage is 2.68 mg three times daily. Many patients respond favorably to a single dose which may be repeated as required, but not to exceed three tablets daily.
Off-Label Use and Dosage (Adult)
Guideline-Supported Use
There is limited information regarding Off-Label Guideline-Supported Use of Clemastine in adult patients.
Non–Guideline-Supported Use
There is limited information regarding Off-Label Non–Guideline-Supported Use of Clemastine in adult patients.
Pediatric Indications and Dosage
FDA-Labeled Indications and Dosage (Pediatric)
Safety and efficacy of clemastine fumarate have not been established in children under the age of 12 years.
Off-Label Use and Dosage (Pediatric)
Guideline-Supported Use
There is limited information regarding Off-Label Guideline-Supported Use of Clemastine in pediatric patients.
Non–Guideline-Supported Use
There is limited information regarding Off-Label Non–Guideline-Supported Use of Clemastine in pediatric patients.
Contraindications
Use in Nursing Mothers
Because of the higher risk of antihistamines for infants generally and for newborns and prematures in particular, antihistamine therapy is contraindicated in nursing mothers.
Use in Lower Respiratory Disease
Antihistamines should not be used to treat lower respiratory tract symptoms including asthma.
Antihistamines are also contraindicated in the following conditions:
Hypersensitivity to clemastine fumarate or other antihistamines of similar chemical structure.
Monoamine oxidase inhibitor therapy
Warnings
Antihistamines should be used with considerable caution in patients with: narrow angle glaucoma, stenosing peptic ulcer, pyloroduodenal obstruction, symptomatic prostatic hypertrophy, and bladder neck obstruction.
Use with CNS Depressants
Clemastine has additive effects with alcohol and other CNS depressants (hypnotics, sedatives, tranquilizers, etc.)
Use in Activities Requiring Mental Alertness
Patients should be warned about engaging in activities requiring mental alertness such as driving a car or operating appliances, machinery, etc.
Precautions
General
Clemastine fumarate should be used with caution in patients with: history of bronchial asthma, increased intraocular pressure, hyperthyroidism, cardiovascular disease, and hypertension.
Adverse Reactions
Clinical Trials Experience
Transient drowsiness, the most common adverse reaction associated with clemastine fumarate, occurs relatively frequently and may require discontinuation of therapy in some instances.
Antihistaminic Compounds
It should be noted that the following reactions have occurred with one or more antihistamines and, therefore, should be kept in mind when prescribing drugs belonging to this class, including clemastine fumarate.
The most frequent adverse reactions are underlined.
Australian Drug Evaluation Committee (ADEC) Pregnancy Category
There is no Australian Drug Evaluation Committee (ADEC) guidance on usage of Clemastine in women who are pregnant.
Labor and Delivery
There is no FDA guidance on use of Clemastine during labor and delivery.
Nursing Mothers
Because of the higher risk of antihistamines for infants generally and for newborns and prematures in particular, antihistamine therapy is contraindicated in nursing mothers.
Pediatric Use
Safety and efficacy of clemastine fumarate have not been established in children under the age of 12 years.
Geriatic Use
Antihistamines are more likely to cause dizziness, sedation, and hypotension in elderly patients.
Gender
There is no FDA guidance on the use of Clemastine with respect to specific gender populations.
Race
There is no FDA guidance on the use of Clemastine with respect to specific racial populations.
Renal Impairment
There is no FDA guidance on the use of Clemastine in patients with renal impairment.
Hepatic Impairment
There is no FDA guidance on the use of Clemastine in patients with hepatic impairment.
Females of Reproductive Potential and Males
There is no FDA guidance on the use of Clemastine in women of reproductive potentials and males.
Immunocompromised Patients
There is no FDA guidance one the use of Clemastine in patients who are immunocompromised.
Administration and Monitoring
Administration
Oral
Monitoring
There is limited information regarding Monitoring of Clemastine in the drug label.
Description
IV Compatibility
There is limited information regarding IV Compatibility of Clemastine in the drug label.
Overdosage
Antihistamine overdosage reactions may vary from central nervous system depression to stimulation. Stimulation is particularly likely in children. Atropine-like signs and symptoms: dry mouth; fixed, dilated pupils; flushing; and gastrointestinal symptoms may also occur.
If vomiting has not occured spontaneously the conscious patient should be induced to vomit. This is best done by having him drink a glass of water or milk after which he should be made to gag. Precautions against aspiration must be taken, especially in infants and children.
If vomiting is unsuccessful gastric lavage is indicated within 3 hours after ingestion and even later if large amounts of milk or cream were given beforehand. Isotonic and 1/2 isotonic saline is the lavage solution of choice.
Saline cathartics, such as milk of magnesia, by osmosis draw water into the bowel and therefore, are valuable for their action in rapid dilution of bowel content.
Stimulants should not be used.
Vasopressors may be used to treat hypotension.
Pharmacology
There is limited information regarding Clemastine Pharmacology in the drug label.