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Active ingredient: Chlorpheniramine - Brands, Medical Use, Clinical Data

Brands, Medical Use, Clinical Data

Drug Category

  • Anti-allergic Agents
  • Antipruritics
  • Antihistamines

Dosage Forms

  • Liquid
  • Syrup
  • Tablet
  • Tablet (extended-release)

Brands / Synonyms

Aller-Chlor; Allergican; Allergisan; Antagonate; Atuss DS Suspension; Chlo-Amine; Chlor-Trimeton; Chlor-Trimeton Allergy; Chlor-Trimeton Repetabs; Chlor-Tripolon; Chlorate; Chloropheniramine; Chlorophenylpyridamin; Chlorophenylpyridamine; Chloropiril; Chloroprophenpyridamine; Chlorphen MAL DEX HBR Pseudoeph; Chlorphen MAL Pseudoeph; Chlorphenamine; Chlorpheniramine Maleate; Chlorprophenpyridamine; Clorfeniramina; Cloropiril; Codeprex Pennkinetic; Dallergy; Dexchlorpheniramine; Dexchlorpheniramine Maleate; Dihydro; Efidac 24 Chlorpheniramine Maleate; Gen-Allerate; Haynon; Histadur; Hycomine; Kloromin; Lexuss; Mylaramine; Novo-Pheniram; Pediacare Allergy Formula; Phenetron; Piriton; Polaramine; Polaronil; Pyridamal 100; Telachlor; Teldrin ; Tussicaps Extended-Release; Tussionex; Tussionex Pennkinetic Extended-Release

Indications

For the treatment of rhinitis, urticaria, allergy, common cold, asthma and hay fever.

Pharmacology

In allergic reactions an allergen interacts with and cross-links surface IgE antibodies on mast cells and basophils. Once the mast cell-antibody-antigen complex is formed, a complex series of events occurs that eventually leads to cell-degranulation and the release of histamine (and other chemical mediators) from the mast cell or basophil. Once released, histamine can react with local or widespread tissues through histamine receptors. Histamine, acting on H1-receptors, produces pruritis, vasodilatation, hypotension, flushing, headache, tachycardia, and bronchoconstriction. Histamine also increases vascular permeability and potentiates pain. Chlorpheniramine, is a histamine H1 antagonist (or more correctly, an inverse histamine agonist) of the alkylamine class. It competes with histamine for the normal H1-receptor sites on effector cells of the gastrointestinal tract, blood vessels and respiratory tract. It provides effective, temporary relief of sneezing, watery and itchy eyes, and runny nose due to hay fever and other upper respiratory allergies.

Mechanism of Action

Chlorpheniramine binds to the histamine H1 receptor. This blocks the action of endogenous histamine, which subsequently leads to temporary relief of the negative symptoms brought on by histamine.

Absorption

Well absorbed in the gastrointestinal tract.

Toxicity

LD50 = 306 mg/kg in humans, mild reproductive toxin to women of childbearing age.

Biotrnasformation / Drug Metabolism

Primarily hepatic via Cytochrome P450 (CYP450) enzymes.

Contraindications

Hypersensitivity to chlorpheniramine maleate or any component of the formulation; narrow-angle glaucoma; bladder neck obstruction; symptomatic prostate hypertrophy; during acute asthmatic attacks; stenosing peptic ulcer; pyloroduodenal obstruction. Avoid use in premature and term newborns due to possible association with SIDS.

Drug Interactions

Substrate of CYP2D6 (minor), 3A4 (major); Inhibits CYP2D6 (weak).

Increased toxicity (CNS depression): CNS depressants, MAO inhibitors, tricyclic antidepressants, phenothiazines.

CYP3A4 inhibitors: May increase the levels/effects of chlorpheniramine. Example inhibitors include azole antifungals, ciprofloxacin, clarithromycin, diclofenac, doxycycline, erythromycin, imatinib, isoniazid, nefazodone, nicardipine, propofol, protease inhibitors, quinidine, and verapamil.

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