1. Name Of The Medicinal Product
Chlorphenamine injection.
2. Qualitative And Quantitative Composition
Each 1ml of solution contains: Chlorphenamine Maleate Ph. Eur. 10mg.
Chlorphenamine is the International Non-proprietary Name and chlorpheniramine is the British Approved Name for the active ingredient of chlorphenamine injection.
3. Pharmaceutical Form
Clear, colourless sterile solution for injection.
4. Clinical Particulars
4.1 Therapeutic Indications
Chlorphenamine injection is indicated for acute urticaria, control of allergic reactions to insect bites and stings, angioneurotic oedema, drug and serum reactions, desensitisation reactions, hayfever, vasomotor rhinitis, severe pruritus of non-specific origin.
4.2 Posology And Method Of Administration
Adults:
The usual dose of chlorphenamine injection for adults is 10mg to 20mg, but not more than 40mg 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 chlorphenamine 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 10mg to 20mg of chlorphenamine injection should be given by the subcutaneous route. This can be repeated to a total of 40mg within a 24-hour period, or oral forms of chlorphenamine may be given until the symptoms subside.
Chlorphenamine 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 10mg.
Chlorphenamine injection cannot, however, be relied on to prevent anaphylactic reactions in patients known to be allergic to a particular drug.
Children:
The dose for children should be calculated, based on either the child's age or their body weight, using the following table:
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Extra care should be taken when preparing the injection for children under 1 year due to the small volumes that are required. Dilution of chlorphenamine injection with sodium chloride intravenous infusion (0.9% w/v) should facilitate preparation. For example, diluting 0.2ml chlorphenamine injection to 2ml with sodium chloride 0.9% injection produces a solution containing chlorphenamine 1mg/ml. The diluted product should be used immediately.
4.3 Contraindications
Chlorphenamine injection is contraindicated in patients who are hypersensitive to antihistamines or to any of the other ingredients.
The anticholinergic properties of chlorphenamine are intensified by monoamine oxidase inhibitors (MAOIs). Chlorphenamine injection is therefore contraindicated in patients who have been treated with MAOIs within the last fourteen days.
4.4 Special Warnings And Precautions For Use
Chlorphenamine, 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.
4.5 Interaction With Other Medicinal Products And Other Forms Of Interaction
Concurrent use of chlorphenamine and hypnotics or anxiolytics may potentiate drowsiness. Concurrent use of alcohol may have a similar effect.
Chlorphenamine inhibits phenytoin metabolism and can lead to phenytoin toxicity.
The anticholinergic effects of chlorphenamine are intensified by MAOIs (see section 4.3 Contraindications).
4.6 Pregnancy And Lactation
There is inadequate evidence of safety in human pregnancy. Chlorphenamine 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 chlorphenamine may inhibit lactation and may be secreted in breast milk. The use of chlorphenamine 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.
4.7 Effects On Ability To Drive And Use Machines
The anticholinergic properties of chlorphenamine may cause drowsiness, blurred vision and psychomotor impairment, which can seriously hamper the patient's ability to drive and use machinery.
4.8 Undesirable Effects
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.
4.9 Overdose
The estimated lethal dose of chlorphenamine is 25mg to 50mg/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.
5. Pharmacological Properties
5.1 Pharmacodynamic Properties
Antihistamines, including chlorphenamine, used in the treatment of allergy act by competing with histamine for H1-receptor sites on cells and tissues. Chlorphenamine also has anticholinergic activity.
The mechanism by which chlorphenamine 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 chlorphenamine, cross the blood-brain barrier and probably produce sedation largely by occupying H1-receptors in the brain.
5.2 Pharmacokinetic Properties
Following iv administration, the apparent steady-state volume of distribution of chlorphenamine is approximately 3L/kg in adults and 3.8L/kg in children.
Chlorphenamine is approximately 70% bound to plasma proteins.
In adults with normal renal and hepatic function, the terminal elimination half-life of chlorphenamine 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.
5.3 Preclinical Safety Data
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.
6. Pharmaceutical Particulars
6.1 List Of Excipients
Sodium chloride, Water for Injections.
6.2 Incompatibilities
In the absence of incompatibility studies, this product must not be mixed with other medicinal products.
6.3 Shelf Life
3 years.
6.4 Special Precautions For Storage
Do not store above 25ºC. Keep the container in the outer carton in order to protect from light.
6.5 Nature And Contents Of Container
Chlorphenamine injection is presented in 1ml neutral glass ampoules. It is supplied in boxes of 5 [or 100*] ampoules. [* not currently marketed.]
6.6 Special Precautions For Disposal And Other Handling
No special requirements.
7. Marketing Authorisation Holder
Archimedes Pharma UK Limited
250 South Oak Way
Green Park
Reading
Berks
RG2 6UG
8. Marketing Authorisation Number(S)
PL 12406/0013.
9. Date Of First Authorisation/Renewal Of The Authorisation
16 December 1999.
10. Date Of Revision Of The Text
3 September 2008.
11. Legal Category
POM
CHLINJU-SPC03
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