Chlorpheniramine maleate

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 PATIENTS > 12 YR

Tablets or syrup

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

SR

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

ER (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.

SR

< 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 sustained-release preparations.

·        Avoid over-the-counter 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.

Adverse effects in Italic are most common; those in Bold are life-threatening.