Clemastine

Pronunciation

(KLEM as teen)

U.S. Brand Names

Dayhist® Allergy [OTC]; Tavist® Allergy [OTC]

Synonyms

Clemastine Fumarate

Generic Available

Yes

Use

Perennial and seasonal allergic rhinitis and other allergic symptoms including urticaria

Pregnancy Risk Factor

Lactation

Enters breast milk/not recommended

Contraindications

Hypersensitivity to clemastine or any component of the formulation; narrow-angle glaucoma

Warnings/Precautions

Safety and efficacy have not been established in children <6 years of age. Use caution with bladder neck obstruction, symptomatic prostate hypertrophy, asthmatic attacks, stenosing peptic ulcer, increased intraocular pressure, hyperthyroidism, cardiovascular disease, hypertension, and in the elderly. May cause drowsiness; use caution in performing tasks which require alertness.

Adverse Reactions

Frequency not defined.

Cardiovascular: Palpitations, hypotension, tachycardia

Central nervous system: Dyscoordination, sedation, slight to moderate somnolence, sleepiness, confusion, restlessness, nervousness, insomnia, irritability, fatigue, headache, increased dizziness

Dermatologic: Rash, photosensitivity

Gastrointestinal: Diarrhea, nausea, xerostomia, epigastric distress, vomiting, constipation

Genitourinary: Urinary frequency, difficult urination, urinary retention

Hematologic: Hemolytic anemia, thrombocytopenia, agranulocytosis

Ocular: Blurred vision

Otic: Tinnitus

Respiratory: Thickening of bronchial secretions

Miscellaneous: Anaphylaxis

Overdosage/Toxicology

Symptoms of overdose include anemia, metabolic acidosis, hypotension, hypothermia

There is no specific treatment for an antihistamine overdose, however, most of its clinical toxicity is due to anticholinergic effects. For anticholinergic overdose with severe life-threatening symptoms, physostigmine 1-2 mg (0.5 mg or 0.02 mg/kg for children) I.V., slowly may be given to reverse these effects.

Drug Interactions

Inhibits CYP2D6 (weak), 3A4 (weak)

Increased toxicity (CNS depression): CNS depressants, MAO inhibitors, tricyclic antidepressants, phenothiazines

Ethanol/Nutrition/Herb Interactions

Ethanol: Avoid ethanol (may increase CNS depression).

Mechanism of Action

Competes with histamine for H1-receptor sites on effector cells in the gastrointestinal tract, blood vessels, and respiratory tract

Pharmacodynamics/Kinetics

Onset of action: Peak effect: Therapeutic: 5-7 hours

Duration: 8-16 hours

Absorption: Almost complete

Metabolism: Hepatic

Excretion: Urine

Dosage

Oral:

Infants and Children <6 years: 0.05 mg/kg/day as clemastine base or 0.335-0.67 mg/day clemastine fumarate (0.25-0.5 mg base/day) divided into 2 or 3 doses; maximum daily dosage: 1.34 mg (1 mg base)

Children 6-12 years: 0.67-1.34 mg clemastine fumarate (0.5-1 mg base) twice daily; do not exceed 4.02 mg/day (3 mg/day base)

Children 12 years and Adults:

1.34 mg clemastine fumarate (1 mg base) twice daily to 2.68 mg (2 mg base) 3 times/day; do not exceed 8.04 mg/day (6 mg base)

OTC labeling: 1.34 mg clemastine fumarate (1 mg base) twice daily; do not exceed 2 mg base/24 hours

Elderly: Lower doses should be considered in patients >60 years

Monitoring Parameters

Look for a reduction of rhinitis, urticaria, eczema, pruritus, or other allergic symptoms

Patient Education

Avoid alcohol; may cause drowsiness, may impair coordination or judgment

Nursing Implications

Raise bed rails, institute safety measures, assist with ambulation

Dental Health: Effects on Dental Treatment

Key adverse event(s) related to dental treatment: Xerostomia (normal salivary flow resumes upon discontinuation).

Dental Health: Vasoconstrictor/Local Anesthetic Precautions

No information available to require special precautions

Mental Health: Effects on Mental Status

Drowsiness is common; may cause nervousness; rare reports of depression

Mental Health: Effects on Psychiatric Treatment

Concurrent use with psychotropics may result in additive sedation

Dosage Forms

Syrup, as fumarate [prescription formulation]: 0.67 mg/5 mL (120 mL) [0.5 mg base/5 mL; contains alcohol 5.5%; citrus flavor]

Tablet, as fumarate: 1.34 mg [1 mg base; OTC], 2.68 mg [2 mg base; prescription formulation]

Dayhist® Allergy, Tavist® Allergy: 1.34 mg [1 mg base]

References

"American Academy of Pediatrics Committee on Drugs. The Transfer of Drugs and Other Chemicals Into Human Milk," Pediatrics , 2001, 108(3):776-89.

Kok TH, Taitz LS, Bennett MJ, et al, "Drowsiness Due to Clemastine Transmitted in Breast Milk," Lancet , 1982, 1:914-5.

International Brand Names

Agasten® (BR); Alagyl® (JP); Alergosan® (YU); Benanzyl® (JP); Clamist® (IN); Clemanil® (JP); Clemastin® (BG, RO); Clemastinum® (PL); Fuluminol® (JP); Inbestan® (JP); Kinotomin® (JP); Lacretin® (JP); Mallermin-F® (JP); Marsthine® (JP); Masletine® (JP); Piloral® (JP); Tavegil® (DE, ES, GB, IT, LU, NL); Tavegyl® (AT, BG, CH, CO, CZ, DK, EG, HU, ID, JO, KW, LB, MT, NO, PT, RO, RU, SE, SI, TR, ZA); Tavist® (MX); Telgin-G® (JP); Xolamin® (JP)

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is the first of its kind, requiring compliance with 53 standards of quality and accountability, verified by independent audit. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial process . A.D.A.M. is also a founding member of Hi-Ethics (www.hiethics.com) and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997-2007 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

Home > Medical Reference > Complementary Medicine