CHLORPHENIRAMINE MALEATE
| CHLORPHENIRAMINE MALEATE (klor-fen-eer'a-meen) Aller-Chlor, Chlo-Amine, Chlor-Trimeton, Chlor-Tripolon  , Novopheniram , Phenetron, Telachlor, Teldrin, TrymeganClassifications: antihistamine (h1-receptor antagonist); Therapeutic: antihistamine; h1-receptor antagonist Prototype: Diphenhydramine Pregnancy Category: B first and second trimester; D third trimester |
Availability
2 mg, 4 mg tablets; 8 mg, 12 mg sustained-release tablets; 2 mg/5 mL syrup
Action
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. Produces less drowsiness than other H1-histamine antagonists.
Therapeutic Effect
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), premature and newborn infants; during or within 14 d of MAO INHIBITOR therapy.
Cautious Use
Convulsive disorders, increased intraocular pressure, hyperthyroidism, cardiovascular disease, hepatic disease; BPH; GI obstruction; hypertension, diabetes mellitus, history of bronchial asthma, COPD, older adult patients, patients with G6PD deficiency, lactation.
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 |
Administration
Oral- Give on an empty stomach for fastest response.
- Sustained-release tablets should be swallowed whole and not crushed or chewed.
- Ensure that chewable tablets are chewed or crushed before being swallowed with a liquid.
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. Metabolism: By CYP3A4. Half-Life: 12–43 h.Nursing Implications
Assessment & Drug Effects
- Monitor for CNS depression and sedation, especially when chlorpheniramine is given in combination with other CNS depressants.
- Monitor BP in hypertensive patients since chlorpheniramine may elevate BP.
Patient & Family Education
- Avoid driving a car and other potentially hazardous activities until drug response has been determined.
- Avoid or minimize alcohol intake. Antihistamines have additive effects with alcohol.
- Report any of the following: tinnitus or palpitations.
- Consult physician before taking additional OTC drugs for allergy relief.
Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; 
Prototype drug