Adult: 4 mg 4-6 hourly. Max: 24 mg daily. Child: 1-2 years 1 mg bid. Max: 4 mg daily. 2-5 years 1 mg 4-6 hourly. Max: 6 mg daily. 6-12 years 2 mg 4-6 hourly. Max: 12 mg daily. >12 years Same as adult dose. Elderly: Dose reduction may be needed. Max: 12 mg daily.
Parenteral Allergic conditions
Adult: 10-20 mg via IM, SC or slow IV inj over 1 minute. Max: 40 mg daily. Child: 1 month to 1 year 0.25 mg/kg. >1-5 years 2.5-5 mg. 6-12 years 5-10 mg. >12 years Same as adult dose.
May be taken with or without food.
Incompatible with Ca chloride, kanamycin sulfate, noradrenaline acid tartrate, pentobarbital Na, and meglumine adipiodone.
Acute asthma, narrow-angle glaucoma, bladder neck obstruction, symptomatic prostate hypertrophy, stenosing peptic ulcer. Concomitant or within 14 days of MAOI use.
Patient with epilepsy, increased intra-ocular pressure, glaucoma, prostatic hyperthrophy, severe CV disease (e.g. ischaemic heart disease, hypertension), urinary retention, pyloroduodenal obstruction, bronchitis, bronchiectasis, thyrotoxicosis. Children and elderly. Pregnancy and lactation.
Significant: CNS depression. Cardiac disorders: Palpitations, tachycardia. Eye disorders: Blurred vision, diplopia. Gastrointestinal disorders: Nausea, dry mouth, abdominal pain, diarrhoea. General disorders and administration site conditions: Fatigue. Investigations: Weight gain. Metabolism and nutrition disorders: Anorexia. Musculoskeletal and connective tissue disorders: Arthralgia. Nervous system disorders: Sedation, disturbance in attention, abnormal coordination, dizziness, headache, excitability. Psychiatric disorders: Somnolence. Renal and urinary disorders: Urinary retention, polyuria. Respiratory, thoracic and mediastinal disorders: Pharyngitis.
Patient Counseling Information
This drug may cause drowsiness, dizziness, blurred vision and psychomotor impairment, if affected, do not drive or operate machinery.
Symptoms: Sedation, paradoxical excitation of the CNS, toxic psychosis, apnoea, convulsions, dystonic reactions, cardiovascular collapse during arrhythmias. Management: Symptomatic and supportive treatment. May employ activated charcoal. Treat convulsions with IV diazepam. My use haemoperfusion in severe cases.
May enhance sedative effect of hypnotics, anxiolytics, sedatives, opioid analgesics and neuroleptics. May inhibit phenytoin metabolism which may lead to phenytoin toxicity. Potentially Fatal: Increased anticholinergic effects with MAOIs.
Increased CNS depression with alcohol.
May react to skin test antigen, suppressing the wheal and flare reaction.
Description: Chlorphenamine is an antihistamine which competitively inhibits histamine H1- receptor in the gastrointestinal and respiratory tract and blood vessels. Thus, prevents the release of histamine, prostaglandins and leukotrienes and prevents the migration of inflammatory mediators. Synonym: Chlorpheniramine Onset: Within 30 minutes. Duration: 4-6 hours. Pharmacokinetics: Absorption: Readily absorbs from the gastrointestinal tract. Bioavailability: 25-50%. Time to peak plasma concentration: 2-3 hours. Distribution: Widely distributed in the body and CNS. Enters breast milk. Volume of distribution: 6-12L/kg. Plasma protein binding: Approx 70%. Metabolism: Undergoes extensive first-pass metabolism in the liver t by CYP450 enzymes to active and inactive metabolites. Excretion: Via urine (22% as unchanged drug); faeces (trace amounts). Elimination half-life: 2-43 hours.