Chlorpheniramine

Pronunciation

(klor fen IR a meen)

U.S. Brand Names

Aller-Chlor® [OTC]; Chlorphen [OTC]; Chlor-Trimeton® [OTC]; Diabetic Tussin® Allergy Relief [OTC]; Teldrin® HBP [OTC]

Synonyms

Chlorpheniramine Maleate; CTM

Generic Available

Yes

Canadian Brand Names

Chlor-Tripolon®; Novo-Pheniram

Use

Perennial and seasonal allergic rhinitis and other allergic symptoms including urticaria

Pregnancy Risk Factor

Contraindications

Hypersensitivity to chlorpheniramine maleate or any component of the formulation; narrow-angle glaucoma; bladder neck obstruction; symptomatic prostate hypertrophy; during acute asthmatic attacks; stenosing peptic ulcer; pyloroduodenal obstruction. Avoid use in premature and term newborns due to possible association with SIDS.

Warnings/Precautions

Causes sedation, caution must be used in performing tasks which require alertness (eg, operating machinery or driving). Sedative effects of CNS depressants or ethanol are potentiated. Use with caution in patients with angle-closure glaucoma, pyloroduodenal obstruction (including stenotic peptic ulcer), urinary tract obstruction (including bladder neck obstruction and symptomatic prostatic hyperplasia), hyperthyroidism, increased intraocular pressure, and cardiovascular disease (including hypertension and tachycardia). High sedative and anticholinergic properties, therefore may not be considered the antihistamine of choice for prolonged use in the elderly. May cause paradoxical excitation in pediatric patients, and can result in hallucinations, coma, and death in overdose.

Adverse Reactions

>10%:

Central nervous system: Slight to moderate drowsiness

Respiratory: Thickening of bronchial secretions

1% to 10%:

Central nervous system: Headache, excitability, fatigue, nervousness, dizziness

Gastrointestinal: Nausea, xerostomia, diarrhea, abdominal pain, appetite increase, weight gain

Genitourinary: Urinary retention

Neuromuscular & skeletal: Arthralgia, weakness

Ocular: Diplopia

Renal: Polyuria

Respiratory: Pharyngitis

Drug Interactions

Substrate of CYP2D6 (minor), 3A4 (major); Inhibits CYP2D6 (weak)

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

CYP3A4 inhibitors: May increase the levels/effects of chlorpheniramine. Example inhibitors include azole antifungals, ciprofloxacin, clarithromycin, diclofenac, doxycycline, erythromycin, imatinib, isoniazid, nefazodone, nicardipine, propofol, protease inhibitors, quinidine, and verapamil.

Ethanol/Nutrition/Herb Interactions

Ethanol: Avoid ethanol (may increase CNS depression).

Stability

Protect from light

Mechanism of Action

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

Pharmacodynamics/Kinetics

Half-life elimination, serum: 20-24 hours

Dosage

Children: Oral: 0.35 mg/kg/day in divided doses every 4-6 hours

2-6 years: 1 mg every 4-6 hours, not to exceed 6 mg in 24 hours

6-12 years: 2 mg every 4-6 hours, not to exceed 12 mg/day or sustained release 8 mg at bedtime

Children >12 years and Adults: Oral: 4 mg every 4-6 hours, not to exceed 24 mg/day or sustained release 8-12 mg every 8-12 hours, not to exceed 24 mg/day

Elderly: Oral: 4 mg once or twice daily. Note: Duration of action may be 36 hours or more when serum concentrations are low.

Hemodialysis: Supplemental dose is not necessary

Administration

Timed release oral forms are to be swallowed whole, not crushed or chewed.

Dietary Considerations

May be taken with food or water.

Patient Education

May cause drowsiness; swallow whole, do not crush or chew sustained release product; avoid alcohol, may impair coordination and judgment

Nursing Implications

Raise bed rails, institute safety measures, assist with ambulation.

Additional Information

Not effective for nasal stuffiness.

Dental Health: Effects on Dental Treatment

Key adverse event(s) related to dental treatment: Xerostomia (normal salivary flow resumes upon discontinuation). Chronic use of antihistamines will inhibit salivary flow, particularly in elderly patients; this may contribute to periodontal disease and oral discomfort.

Dental Health: Vasoconstrictor/Local Anesthetic Precautions

No information available to require special precautions

Mental Health: Effects on Mental Status

Drowsiness is common; may cause excitability, nervousness, fatigue, or depression

Mental Health: Effects on Psychiatric Treatment

Dry mouth and sedation may be exacerbated by concurrent psychotropic use

Dosage Forms

Syrup, as maleate:

Aller-Chlor®: 2 mg/5 mL (120 mL) [contains alcohol 5%]

Diabetic Tussin® Allergy Relief: 2 mg/5 mL (120 mL) [alcohol free, dye free, sugar free]

Tablet, as maleate (Aller-Chlor®, Chlor-Trimeton®, Chlorphen, Teldrin® HBP): 4 mg

Tablet, extended release, as maleate (Chlor-Trimeton®): 12 mg

International Brand Names

Chlor-Tripolon® (CA); Novo-Pheniram (CA)

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