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; T_1/2: 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
• Hematologic: Hemolytic 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.

Posted in: Pharmacology