Chlorpheniramine Injection 20mg/2mL | Antihistamine Allergy

Product Description

1. Composition

Each 2 ml of solution contains 20 mg chlorphenamine maleate BP.

2. Pharmacological Action

Antihistamines, including chlorphenamine, exert their therapeutic effect in allergy by competing with histamine for H-receptor sites on cells and tissues. Chlorphenamine also has anticholinergic activity.

The mechanism underlying the anti-emetic, anti-motion sickness and anti-vertigo effects of chlorphenamine is not fully elucidated, but may be associated with its central nervous system actions. Furthermore, most antihistamines including chlorphenamine cross the blood-brain barrier, and produce sedation largely by occupying central H-receptors.

3. Indications

Chlorphenamine Maleate Injection is indicated for:

• Acute urticaria
• Control of allergic reactions to insect bites and stings
• Angioneurotic oedema
• Drug and serum reactions
• Desensitisation reactions
• Hay fever
• Vasomotor rhinitis
• Severe pruritus of non-specific origin

4. Dosage and Directions for Use

This product may be administered by subcutaneous, intramuscular or intravenous injection.

Adults

The usual adult dose is 10 mg to 20 mg, with a maximum daily dose of 40 mg within a 24-hour period.

• Anaphylactic reactions: When a rapid onset of action is required, intravenous administration is recommended as an adjunct to standard emergency therapy (adrenaline/epinephrine, corticosteroids, oxygen and supportive care as clinically indicated). The injection should be administered slowly over at least 1 minute, using the smallest appropriate syringe. Any subsequent drowsiness, giddiness or hypotension is usually transient.
• Blood transfusion reactions: 10 mg to 20 mg by subcutaneous injection. The dose may be repeated up to a total of 40 mg within 24 hours, or oral formulations may be used until symptoms subside.
• Prophylaxis of delayed drug reactions: May be used to reduce the risk of delayed allergic reactions to penicillin and other drugs, administered by separate intramuscular injection immediately before the causative drug. The usual dose is 10 mg.

Important: This product cannot be relied upon to prevent anaphylactic reactions in patients with known drug hypersensitivity.

Paediatric population

Dosage should be calculated according to age or body weight, as shown in the table below:

Age group	Dose by age		Dose by body weight
1 month to 1 year	–		0.25 mg/kg
1 to 5 years	2.5 mg to 5 mg	OR	0.20 mg/kg
6 to 12 years	5 mg to 10 mg	OR	0.20 mg/kg
12 to 18 years	10 mg to 20 mg	OR	0.20 mg/kg

Extra caution is required when preparing doses for infants under 1 year of age, due to the small volumes involved. Dilution with 0.9% w/v sodium chloride intravenous infusion is recommended to ensure accurate dosing.

Example: Dilute 0.2 ml of the product to 2 ml with 0.9% sodium chloride injection, to obtain a solution containing 1 mg/ml chlorphenamine maleate. The diluted solution must be used immediately.

5. Contraindications

• Hypersensitivity to chlorphenamine, other antihistamines, or any excipient in the formulation.
• Use in patients receiving monoamine oxidase inhibitors (MAOIs), or within 14 days of discontinuing MAOI therapy, as MAOIs potentiate the anticholinergic effects of chlorphenamine.

6. Warnings and Precautions

As with other medicinal products with anticholinergic activity, this injection should be used with caution in patients with:

• Epilepsy
• Raised intra-ocular pressure, including glaucoma
• Prostatic hypertrophy
• Severe hypertension or cardiovascular disease
• Bronchitis, bronchiectasis and asthma
• Hepatic impairment
• Thyrotoxicosis

Children and elderly patients are more susceptible to neurological anticholinergic adverse effects.

7. Undesirable Effects

The most common adverse reaction is sedation, ranging from mild drowsiness to deep sleep.

• Other effects that may occur occasionally include:
• Impaired concentration, lassitude, blurred vision
• Gastrointestinal disturbances: nausea, vomiting, diarrhoea
• Urinary retention, headache, dry mouth, dizziness, palpitations, dyspepsia, anorexia
• Hepatitis (including jaundice), thickened bronchial secretions
• Haemolytic anaemia and other blood dyscrasias
• Hypersensitivity reactions: exfoliative dermatitis, photosensitivity, skin rashes, urticaria
• Muscle twitching, muscular weakness and incoordination, tinnitus
• Depression, irritability, nightmares (infrequent)

Paradoxical excitation may occur in children, and confusional psychosis may occur in elderly patients. Local stinging or burning at the injection site has been reported. Rapid intravenous injection may cause transient hypotension or central nervous system stimulation.

8. Storage Instructions

Store at controlled room temperature (25°C / 77°F) and protect from light. Keep this medicine out of the reach of children.

9. Pack Information

Available in packs containing 10 ampoules of 2 ml per box.