Chlorphenamine information from DrugsUpdate
L - Caution when used during lactation
FI - Food *
Chlorpheniramine, commonly marketed as its salt chlorphenamine maleate (CPM; Chlor-Trimeton, Piriton, Chlor-Tripolon), is a first-generation alkylamine antihistamine used in the prevention of the symptoms of allergic conditions such as rhinitis and urticaria. Its sedative effects are relatively weak compared to other first-generation antihistamines. Chlorpheniramine is one of the most commonly-used antihistamines in small-animal veterinary practice as well. Although not generally approved as an antidepressant or anti-anxiety medication, chlorpheniramine appears to have these properties as well.
Chlorpheniramine is part of a series of antihistamines including pheniramine (Naphcon) and its halogenated derivatives and others including fluorpheniramine, dexchlorpheniramine (Polaramine), brompheniramine (Dimetapp), dexbrompheniramine (Drixoral), deschlorpheniramine, dipheniramine (also known as triprolidine with the trade name Actifed), and iodopheniramine.
The halogenated alkylamine antihistamines all exhibit optical isomerism, and chlorpheniramine in the indicated products is racemic chlorpheniramine maleate, whereas dexchlorpheniramine (Polaramine) is the dextrorotary (right-handed) stereoisomer.
It is also known as Comakin in Taiwan and parts of Asia.
Chlorphenamine is an H1-receptor antagonist which competetively blocks H1-receptor sites on tissues.
Absorbed relatively slowly from the GI tract (oral); peak plasma concentrations after 2.5-6 hours.
Widely distributed; CNS. Protein-binding: 70%.
Extensive; converted to desmethyl- and didesmethylchlorphenamine.
Via urine (as unchanged drug and metabolites).
CNS depression, sedation, drowsiness, lassitude, dizziness. GI upsets, anorexia, or increased appetite, epigastric pain, blurring of vision, dysuria, dryness of mouth, tightness in chest, hypotension, muscular weakness, tinnitus, euphoria, headache, paradoxical CNS stimulation.
Potentially Fatal: CV collapse and respiratory failure.
Elderly, pylori duodenal obstruction, angle-closure glaucoma, urinary retention, prostatic hyperplasia, epilepsy, renal and hepatic impairment. May affect performance of skilled tasks. BPH, bladder neck obstruction, hypertension. Pregnancy, lactation.
Potentiates sedative effect of psychotropic drugs e.g. barbiturates, hypnotics, opiod analgesics, anxiolytics and antipsychotics. Interaction with alcohol could be dangerous (sedation/excitation).
Food Interactions: Reduced bioavailability
Oral Allergic conditions
Adult: 4 mg every 4-6 hours. Max: 24 mg daily.
Child: 1-2 years: 1 mg bid, 2-5 years: 1 mg every 4-6 hours, 6-12 years: 2 mg every 4-6 hours. Max: 6 mg daily (1-5 years); 12 mg daily (6-12 years).
Parenteral Adjunct in the emergency treatment of anaphylactic shock
Adult: 10-20 mg IM, SC, or slow IV injection over 1 minute. Max dose: 40 mg daily.
Child: 87.5 mcg/kg SC 4 times daily
Incompatible with calcium chloride, kanamycin sulfate, noradrenaline acid tartrate, pentobarbital sodium and meglumine adipiodone.