Allerfin 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.

 

Adults:
The usual dose of chlorpheniramine injection for adults is 10 mg to 20 mg, but not more than 40 mg should be given within a 24-hour period. The injection may be given by the subcutaneous, intramuscular or intravenous route.

When a rapid effect is desired, as in anaphylactic reactions, the intravenous route is recommended in addition to emergency therapy with adrenaline (epinephrine), corticosteroids, oxygen and supportive therapy as required. In this case chlorpheniramine injection should be injected slowly over a period of one minute, using the smallest adequate syringe. Any drowsiness, giddiness or hypotension which may follow is usually transitory.

In the event of a blood transfusion reaction, a dose of 10 mg to 20 mg of chlorpheniramine injection should be given by the subcutaneous route. This can be repeated to a total of 40 mg within a 24-hour period, or oral forms of chlorpheniramine may be given until the symptoms subside.

Chlorpheniramine injection may be helpful in the prevention of delayed reactions to penicillin and other drugs when given separately by intramuscular injection immediately prior to administration of the other drug. The usual dose is 10 mg.

Chlorpheniramine injection cannot, however, be relied on to prevent anaphylactic reactions in patients known to be allergic to a particular drug.

Paediatric population:
The dose for children should be calculated, based on either the child's age or their body weight, using the following table:

Age	Dose
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 care should be taken when preparing the injection for children under 1 year due to the small volumes that are required. Dilution of chlorpheniramine injection with sodium chloride intravenous infusion (0.9% w/v) should facilitate preparation. For example, diluting 0.2 ml chlorpheniramine injection to 2 ml with sodium chloride 0.9% injection produces a solution containing chlorpheniramine 1 mg/ml.

For instruction on dilution of the product before administration, see section 6.6. For shelf-life and storage conditions after dilution of the medicinal product, see sections 6.3 and 6.4.

Hypersensitivity to the active substance, antihistamines or to any of the excipients listed in section 6.1. Use in pre-coma states. The anticholinergic properties of chlorpheniramine are intensified by monoamine oxidase inhibitors (MAOIs). Chlorpheniramine injection is therefore contraindicated in patients who have been treated with MAOIs within the last fourteen days.

Chlorpheniramine, in common with other drugs having anticholinergic effects, should be used with caution in epilepsy; raised intra-ocular pressure including glaucoma; prostatic hypertrophy; severe hypertension or cardiovascular disease; bronchitis; bronchiectasis and asthma; hepatic disease and thyrotoxicosis. Children and the elderly are more likely to experience the neurological anticholinergic effects.

Allerfin contains benzyl alcohol, potassium, sodium and sodium metabisulphite
Allerfin contains benzyl alcohol. Each ampoule of Allerfin 10 mg/ml Solution for Injection contains 15 mg benzyl alcohol:

• Benzyl alcohol may cause allergic reactions.
• Intravenous administration of benzyl alcohol has been associated with serious adverse events and death in neonates (“gasping syndrome”). The minimum amount of benzyl alcohol at which toxicity may occur is not known.
  Do not give to newborn babies (up to 4 weeks old), unless considered essential.
• Increased risk due to accumulation in young children. Do not use for more than a week in young children (less than 3 years old), unless considered essential.
• High volumes should be used with caution and only if necessary, especially in subjects who are pregnant or breast-feeding or are with liver or kidney impairment because of the risk of accumulation and toxicity (metabolic acidosis).

Allerfin contains potassium. Each ampoule of Allerfin 10 mg/ml Solution for Injection contains 0.0264 mmol (1.03 mg) potassium. This medicine contains potassium, less than 1 mmol potassium (39 mg) per ampoule, i.e. essentially ‘potassium-free’.

Allerfin contains sodium. Each ampoule of Allerfin 10 mg/ml Solution for Injection contains 0.0813 mmol (1.87 mg) sodium. This medicine contains less than 1 mmol sodium (23 mg) per ampoule, that is to say essentially ‘sodium-free’.

Allerfin contains sodium metabisulphite. Each ampoule of Allerfin 10 mg/ml Solution for Injection contains 1 mg sodium metabisulphite. It may rarely cause severe hypersensitivity reactions and bronchospasm.

Concurrent use of chlorpheniramine and hypnotics or anxiolytics may potentiate drowsiness. Concurrent use of alcohol may have a similar effect.

Chlorpheniramine inhibits phenytoin metabolism and can lead to phenytoin toxicity.

The anticholinergic effects of chlorpheniramine are intensified by MAOIs (see section 4.3).

There is inadequate evidence of safety in human pregnancy. Chlorpheniramine injection should only be used during pregnancy when clearly needed and when the potential benefits outweigh the potential unknown risks to the foetus. Use during the third trimester may result in reactions in neonates.

It is reasonable to assume that chlorpheniramine may inhibit lactation and may be secreted in breast milk. The use of chlorpheniramine injection in mothers breast-feeding their babies requires that the therapeutic benefits of the drug should be weighed against the potential hazards to the mother and baby.

The anticholinergic properties of chlorpheniramine may cause drowsiness, blurred vision and psychomotor impairment, which can seriously hamper the patient's ability to drive and use machinery.

The most common side-effect is sedation varying from slight drowsiness to deep sleep. The following may also occasionally occur: inability to concentrate; lassitude; blurred vision; gastro-intestinal disturbances such as nausea, vomiting and diarrhoea.

Urinary retention; headaches; dry mouth; dizziness; palpitation; painful dyspepsia; anorexia; hepatitis including jaundice; thickening of bronchial secretions; haemolytic anaemia and other blood dyscrasias; allergic reactions including exfoliative dermatitis, photosensitivity, skin reactions and urticaria; twitching, muscular weakness and incoordination; tinnitus; depression; irritability and nightmares infrequently occur.

Paradoxical excitation in children and confusional psychosis in the elderly can occur.

Some patients have reported a stinging or burning sensation at the site of injection. Rapid intravenous injection may cause transitory hypotension or CNS stimulation.

Reporting of suspected adverse reactions
Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via:

• Saudi Arabia

The National Pharmacovigilance Centre (NPC)

SFDA Call Center: 19999
E-mail: npc.drug@sfda.gov.sa

Website: https://ade.sfda.gov.sa

• Other GCC States

Please contact the relevant competent authority.

The estimated lethal dose of chlorpheniramine is 25 mg to 50 mg/kg body weight. Symptoms and signs include sedation, paradoxical stimulation of the CNS, toxic psychosis, seizures, apnoea, convulsions, anticholinergic effects, dystonic reactions and cardiovascular collapse including arrhythmias.

Symptomatic and supportive measures should be provided with special attention to cardiac, respiratory, renal and hepatic functions, and fluid and electrolytic balance. If overdosage is by the oral route, treatment should include gastric lavage or induced emesis using syrup of ipecacuanha. Following these measures activated charcoal and cathartics may be administered to minimise absorption.

Treat hypotension and arrhythmias vigorously. CNS convulsions may be treated with iv diazepam. Haemoperfusion may be used in severe cases.

Pharmacotherapeutic group: Antihistamines for systemic use

ATC code: R06AB04

Antihistamines, including chlorpheniramine, used in the treatment of allergy act by competing with histamine for H₁-receptor sites on cells and tissues. Chlorpheniramine also has anticholinergic activity.

The mechanism by which chlorpheniramine exerts its anti-emetic, anti- motion sickness and anti-vertigo effects is not precisely known but may be related to its central actions. Further, most antihistamines, including chlorpheniramine, cross the blood-brain barrier and probably produce sedation largely by occupying H₁-receptors in the brain.

Following iv administration, the apparent steady-state volume of distribution of chlorpheniramine is approximately 3 L/kg in adults and 3.8 L/kg in children.

Chlorpheniramine is approximately 70% bound to plasma proteins.

In adults with normal renal and hepatic function, the terminal elimination half-life of chlorpheniramine reportedly ranges from 12 to 43 hours.

The systemic exposure per mg dose is lower in children than adults and the elimination half-life may be shorter.

There are no pre-clinical data of relevance to the prescriber which are additional to that already included in other sections of the Summary of Product Characteristics.

• Citric acid
• Potassium citrate
• Disodium edetate
• Sodium metabisulphite
• Sodium chloride
• Benzyl alcohol
• Water for injection

In the absence of incompatibility studies, this product must not be mixed with other medicinal products.

Unopened: 36 months. The injection should be given immediately after opening the ampoule. Once opened, any unused portion should be discarded. After dilution: Chemical and physical in-use stability has been demonstrated for 24 hours at 2-8°C. From a microbiological point of view, the product should be used immediately. If not used immediately, in-use storage times and conditions prior to use are the responsibility of the user and would normally not be longer than 24 hours at 2 to 8°C, unless dilution has taken place in controlled and validated aseptic conditions.

Store below 30°C.

Store in the original package in order to protect from light.

For storage conditions after dilution of the medicinal product, see section 6.3.

Amber glass type I ampoule.

Pack size: 5 Ampoules (1 ml).

Use in the paediatric population
Due to the small volumes that are required for children under one year of age, chlorpheniramine injection may be diluted with sodium chloride 0.9% injection to produce a solution containing chlorpheniramine 1 mg/ml. For example, 0.2 ml chlorpheniramine injection may be diluted to 2 ml with sodium chloride 0.9% injection immediately prior to administration. See section 4.2 for details of paediatric dosing.

The diluted solution should be inspected visually for particulate matter and discoloration prior to administration. In the event of either being observed, discard the medicinal product. Only clear solution should be used. See section 6.3 for details regarding the shelf-life of the diluted solution.

This medicinal product is for single use only.

If the entire reconstituted content of the ampoule is not required, any unused solution should be discarded in accordance with local requirements.