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clemastine

D04AA14

Forms & Strengths

Oral syrup: 0.67 mg/5 mL
Oral tablet: 1.34 mg, 2.68 mg

Adult Dosing

Allergic rhinitis and urticaria: 1.34 mg orally twice daily; maximum 8.34 mg daily
Pruritus: 1.34 mg to 2.68 mg orally twice daily as needed

Pediatric Dosing

Children 6 to 12 years: 0.67 mg to 1.34 mg orally twice daily; maximum 4.02 mg daily
Children under 6 years: Safety and efficacy not established

Indications

Symptomatic relief of allergic rhinitis such as sneezings, rhinorrhea, and pruritus
Management of allergic conjunctivitis due to inhalant allergens and foods
Mild, uncomplicated allergic skin manifestations of urticaria and angioedema
Pruritus associated with histamine-mediated conditions

Mechanism of Action

First-generation ethanolamine-derivative antihistamine with H1-receptor antagonistic properties
Possesses significant anticholinergic and sedative effects
Competes with free histamine for H1-receptor sites on effector cells in the gastrointestinal tract, blood vessels, and respiratory tract

Contraindications

Hypersensitivity to clemastine or other antihistamines of similar chemical structure
Concurrent use with monoamine oxidase inhibitors (MAOIs)
Narrow-angle glaucoma
Symptomatic prostatic hypertrophy
Stenosing peptic ulcer and pyloroduodenal obstruction

Adverse Reactions

Drowsiness, sedation, dizziness, and disturbed coordination
Anticholinergic effects including dry mouth, blurred vision, urinary retention, and constipation
Epigastric distress, nausea, and vomiting
Paradoxical excitation in young children

Drug Interactions

Central nervous system depressants (alcohol, barbiturates, hypnotics, sedatives) enhance sedative effects
Monoamine oxidase inhibitors (MAOIs) prolong and intensify the anticholinergic effects of antihistamines
Drugs with significant anticholinergic activity (tricyclic antidepressants) may result in additive anticholinergic side effects

Curated Content: Needs Vetting Before Put to Clinical Use