Indication

Urticaria, Sneezing, Watery eyes, Allergic conditions, Anaphylactic shock, Rhinitis, Itching

Adult Dose

Oral Adult: 4 mg every 4-6 hr. Max: 24 mg daily. Parenteral Adjunct in the emergency treatment of anaphylactic shock Adult: 10-20 mg IM, SC, or slow IV inj over 1 min. Max dose: 40 mg daily.

Child Dose

Oral Child: 1-2 yr: 1 mg bid, 2-5 yr: 1 mg every 4-6 hr, 6-12 yr: 2 mg every 4-6 hr. Max: 6 mg daily (1-5 yr); 12 mg daily (6-12 yr). Parenteral Adjunct in the emergency treatment of anaphylactic shock Child: 87.5 mcg/kg SC 4 times daily

Contraindication

Hypersensitivity, Neonates.

Mode of Action

Chlorphenamine is an H1-receptor antagonist which competetively blocks H1-receptor sites on tissues.

Precaution

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.

Side Effect

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.

Pregnancy Category Note

Pregnancy Antihistamine exposure in first trimester not reported to be associated with increased risk of malformations; animal studies not reported; there are no controlled data in human pregnancy; only recommended for use during pregnancy when benefit outweighs risk Lactation Excretion into human milk; the manufacturer recommends that caution be used when administering chlorpheniramine to nursing women; infants should be monitored for irritability or drowsiness; antihistamines may temporarily decrease maternal serum prolactin concentrations when administered prior to nursing infant for the first time

Interaction

Potentiates sedative effect of psychotropic drugs e.g. barbiturates, hypnotics, opioid analgesics, anxiolytics and antipsychotics. Interaction with alcohol could be dangerous (sedation/excitation).