CHLORPHENIRAMINE MALEATE
(klor-fen-eer'a-meen)
Aller-Chlor, Chlo-Amine, Chlorate, Chlor-Pro, Chlorspan, Chlortab, Chlor-Trimeton, Chlor-Tripolon , Novopheniram , Pfeiffer Allergy, Phenetron, Telachlor, Teldrin, Trymegan
Classifications: antihistamine (h1-receptor antagonist)
Prototype: Diphenhydramine
Pregnancy Category: B first and second trimester; category; D in third trimester

Availability

2 mg, 4 mg tablets; 8 mg, 12 mg sustained-release tablets; 2 mg/5 mL syrup

Actions

Antihistamine that competes with histamine for H1-receptor sites on effector cells, thus it prevents histamine action that promotes capillary permeability and edema formation and constrictive action on respiratory, gastrointestinal, and vascular smooth muscles. It generally produces less drowsiness than other antihistamines, but adverse effects involving CNS stimulation may be more common.

Therapeutic Effects

Has effective antihistamine reaction resulting in decreasing allergic symptomatology.

Uses

Symptomatic relief of various uncomplicated allergic conditions; to prevent transfusion and drug reactions in susceptible patients, and as adjunct to epinephrine and other standard measures in anaphylactic reactions.

Contraindications

Hypersensitivity to antihistamines of similar structure; lower respiratory tract symptoms, narrow-angle glaucoma, obstructive prostatic hypertrophy or other bladder neck obstruction, GI obstruction or stenosis; pregnancy (category B in first and second trimester and category D in third trimester), lactation; premature and newborn infants; during or within 14 d of MAO INHIBITOR therapy.

Cautious Use

Convulsive disorders, increased intraocular pressure, hyperthyroidism, cardiovascular disease, hypertension, diabetes mellitus, history of bronchial asthma, older adult patients, patients with G6PD deficiency.

Route & Dosage

Symptomatic Allergy Relief
Adult: PO 2–4 mg t.i.d. or q.i.d. or 8–12 mg b.i.d. or t.i.d., max: 24 mg/d
Geriatric: PO 4 mg q.d. or b.i.d. or 8 mg sustained-release h.s.
Child: PO 6–12 y: 2 mg q4–6h (max: 12 mg/d); 2–6 y: 1 mg q4–6h

Allergic Reactions to Blood
Adult: SC/IV/IM 10–20 mg (max: 40 mg/d)

Administration

Oral
Subcutaneous/Intramuscular/Intravenous
Intravenous

PREPARE: Direct: Give undiluted.  

ADMINISTER: Direct: Give 10 mg or fraction thereof over at least 1 min.  

  • If patient manifests any reaction after parenteral administration, drug should be discontinued. (Exception: Patient may experience transitory stinging sensation that rarely lasts longer than a few minutes.)

Adverse Effects (1%)

Body as a Whole: Sensation of chest tightness. CV: Palpitation, tachycardia, mild hypotension or hypertension. GI: Epigastric distress, anorexia, nausea, vomiting, constipation, or diarrhea. CNS: Drowsiness, sedation, headache, dizziness, vertigo, fatigue, disturbed coordination, tremors, euphoria, nervousness, restlessness, insomnia. Special Senses: Dryness of mouth, nose, and throat, tinnitus, vertigo, acute labyrinthitis, thickened bronchial secretions, blurred vision, diplopia. Urogenital: Urinary frequency or retention, dysuria.

Diagnostic Test Interference

Antihistamines should be discontinued 4 d before skin testing procedures for allergy because they may obscure otherwise positive reactions.

Interactions

Drug: Alcohol (ethanol) and other cns depressants produce additive sedation and CNS depression.

Pharmacokinetics

Absorption: Well absorbed from GI tract; about 45% of dose reaches systemic circulation intact. Onset: Within 6 h. Peak: 2–6 h. Distribution: Highest concentrations in lung, heart, kidney, brain, small intestine, and spleen. Half-Life: 12–43 h.

Nursing Implications

Assessment & Drug Effects

Patient & Family Education


Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug