WHO Model Prescribing Information: Drugs Used in Skin Diseases
(1997; 132 pages) [French] [Spanish] View the PDF document
Table of Contents
View the documentPreface
View the documentIntroduction
Open this folder and view contentsParasitic infections
Open this folder and view contentsInsect and arachnid bites and stings
Open this folder and view contentsSuperficial fungal infections
Open this folder and view contentsSubcutaneous fungal infections
Open this folder and view contentsBacterial infections
Open this folder and view contentsViral infections
Open this folder and view contentsEczematous diseases
Open this folder and view contentsScaling diseases
Open this folder and view contentsPapulosquamous diseases
View the documentCutaneous reactions to drugs
Open this folder and view contentsPigmentary disorders
Open this folder and view contentsPremalignant lesions and malignant tumours
Open this folder and view contentsPhotodermatoses
Open this folder and view contentsBullous dermatoses
View the documentAlopecia areata
View the documentUrticaria
Open this folder and view contentsConditions common in children
View the documentAcne vulgaris
View the documentPruritus
View the documentTropical ulcers
Open this folder and view contentsAntimicrobial drugs
Open this folder and view contentsAntifugal drugs
Open this folder and view contentsAntiseptic agents
Open this folder and view contentsKeratoplastic and keratolytic agents
Open this folder and view contentsScabicides and pediculicides
Open this folder and view contentsAnti-inflammatory and antipruritic drugs1
Close this folderAntiallergics and drugs used in anaphylaxis
View the documentChlorphenamine
View the documentAlternative antihistamines
View the documentEpinephrine
Open this folder and view contentsUltraviolet radiation-blocking agents (sunscreens)
Open this folder and view contentsMiscellaneous drugs
Open this folder and view contentsAnnex
View the documentSelected WHO Publications of Related Interest
View the documentBack cover
 

Chlorphenamine

Tablet, 4 mg (hydrogen maleate)

General information

Chlorphenamine is an antihistamine that reversibly and competitively inhibits the binding of histamine to H1 receptors.

It is well absorbed following oral administration and is widely distributed throughout the body including the central nervous system. Plasma concentrations peak after 2-3 hours. It is metabolized in the liver and excreted in the urine, largely as metabolites.

Clinical information

Uses

Symptomatic treatment of:

• urticaria
• severe and intractable pruritus.

Dosage and administration

The dosage should be adjusted according to the patient’s response and tolerance.

Adults and children over 12 years: 4 mg every 6 hours.

Children under 12 years: 0.35 mg/kg daily in three or four divided doses.

Contraindications

Age under 2 years.

Precautions

Drowsiness, dizziness, blurred vision and psychomotor impairment can occur. These effects can seriously impair the patient’s ability to drive and use machinery.

Use in pregnancy

Safe use in pregnancy has not been established. Chlorphenamine should be used only when the need of the mother outweighs any possible risk to the fetus.

Adverse effects

Sedation, which can vary in degree from mild drowsiness to deep sleep is common, but patients rapidly develop tolerance. This effect may be of benefit in patients with pruritus. Other adverse effects on the central nervous system include dizziness, lassitude, incoordination and blurred vision. These effects are rarely observed with the newer H1 antagonists, which do not cross the blood-brain barrier.

Paradoxical excitation in children and confusional states in the elderly have been reported.

Gastrointestinal symptoms including anorexia, nausea, vomiting, epigastric pain and constipation or diarrhoea also occur.

Drug interactions

Alcohol and other drugs acting on the brain have an additive sedative effect. Phenytoin toxicity has resulted from inhibition of its metabolism.

Overdosage

Drowsiness, dizziness and ataxia are the most common symptoms of acute overdosage. Anticholinergic effects including flushing, dilated pupils and hyperthermia occur within 2 hours of ingestion. In serious cases, seizures are followed by respiratory and cardiovascular depression.

Induction of emesis or gastric lavage followed by administration of activated charcoal is of value when undertaken within a few hours of ingestion. Treatment is otherwise symptomatic and aims to maintain respiration and control seizures and cardiovascular abnormalities.

Storage

Tablets should be stored in well-closed containers, protected from light.

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