chlorpheniramine

Chlorpheniramine maleate is an antihistamine indicated for symptomatic relief of symptoms associated with perennial and seasonal allergic rhinitis; vasomotor rhinitis; allergic conjunctivitis.

Generic Names & Brand Names
chlorpheniramine maleate

(klor fen ir a meen)

Aller-Chlor; Allergy; Chlo-Amine; Chlor-Trimeton Allergy 4 hr, 8 hr, and
12 hr; Chlor-Tripolon (CAN); Efidac 24

Pregnancy Category B

Drug class

Antihistamine (alkylamine type)

Therapeutic actions

Competitively blocks the effects of histamine at H1-receptor sites; has atropine-like, antipruritic, and sedative effects.

Indications
  • Symptomatic relief of symptoms associated with perennial and seasonal allergic rhinitis; vasomotor rhinitis; allergic conjunctivitis.
Contraindications and cautions
  • Contraindicated with allergy to any antihistamines, narrow-angle glaucoma, stenosing peptic ulcer, symptomatic prostatic hypertrophy, asthmatic attack, bladder neck obstruction, pyloroduodenal obstruction, third trimester of pregnancy, lactation.
  • Use cautiously in pregnancy.
Available forms

Chewable tablets—2 mg; tablets—4 mg; ER tablets—8, 12, 16 mg; syrup—2 mg/5 mL; SR capsules—8, 12 mg

Dosages
ADULTS AND CHILDREN > 12 YR

Tablets or syrup

  • 4 mg PO q 4–6 hr; do not exceed 24 mg in 24 hr.

Sustained-release

  • 8–12 mg PO hs or q 8–12 hr during the day; do not exceed 24 mg in 24 hr.

Extended-release (Efidac 24)

  • 16 mg with liquid PO q 24 hr.
PEDIATRIC PATIENTS

Tablets or syrup

  • 2–< 6 yr: 1 mg q 4–6 hr PO; do not exceed 4 mg in 24 hr.
  • 6–12 yr: 2 mg q 4–6 hr PO; do not exceed 12 mg in 24 hr.

Sustained-release

  • < 6 yr: Not recommended.
  • 6–12 yr: 8 mg PO hs or during the day.

GERIATRIC PATIENTS

  • More likely to cause dizziness, sedation, syncope, toxic confusional states, and hypotension in elderly patients; use with caution.
Pharmacokinetics
Route Onset Peak
Oral 0.5–6 hr 2–6 hr

Metabolism: Hepatic; T1/2: 12–15 hr

Distribution: Crosses placenta; may enter breast milk

Excretion: Urine

Adverse effects
  • CNS: Drowsiness, sedation, dizziness, disturbed coordination, fatigue, confusion, restlessness, excitation, nervousness, tremor, headache, blurred vision, diplopia, vertigo, tinnitus, acute labyrinthitis, hysteria, tingling, heaviness and weakness of the hands
  • CV: Hypotension, palpitations, bradycardia, tachycardia, extrasystoles
  • GI: Epigastric distress, anorexia, increased appetite and weight gain, nausea, vomiting, diarrhea or constipation
  • GU: Urinary frequency, dysuria, urinary retention, early menses, decreased libido, impotence
  • HematologicHemolytic anemia, hypoplastic anemia, thrombocytopenia, leukopenia, agranulocytosis, pancytopenia
  • Respiratory: Thickening of bronchial secretions, chest tightness, wheezing, nasal stuffiness, dry mouth, dry nose, dry throat, sore throat
  • Other: Urticaria, rash, anaphylactic shock, photosensitivity, excessive perspiration, chills
Interactions
Drug-drug
  • Increased depressant effects with alcohol, other CNS depressants
Nursing considerations
Assessment
  • History: Allergy to any antihistamines; narrow-angle glaucoma, stenosing peptic ulcer, symptomatic prostatic hypertrophy, asthmatic attack, bladder neck obstruction, pyloroduodenal obstruction, pregnancy, lactation
  • Physical: Skin color, lesions, texture; orientation, reflexes, affect; vision examination; P, BP; R, adventitious sounds; bowel sounds; prostate palpation; CBC with differential
Interventions
  • Administer with food if GI upset occurs.
  • Caution patient not to crush or chew SR preparations.
  • Arrange for periodic blood tests during prolonged therapy.
Teaching points
  • Take as prescribed; avoid excessive dosage. Take with food if GI upset occurs; do not cut, crush, or chew the SR preparations.
  • Avoid OTC drugs; many contain ingredients that could cause serious reactions if taken with this antihistamine.
  • Avoid alcohol; serious sedation may occur.
  • You may experience these side effects: Dizziness, sedation, drowsiness (use caution driving or performing tasks that require alertness); epigastric distress, diarrhea, or constipation (take with meals; consult care provider if severe); dry mouth (frequent mouth care; sucking on sugarless lozenges may help); thickening of bronchial secretions, dryness of nasal mucosa (use a humidifier).
  • Report difficulty breathing; hallucinations, tremors, loss of coordination; unusual bleeding or bruising; visual disturbances; irregular heartbeat.