Treatment with adrenaline (epinephrine)

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Treatment with adrenaline (epinephrine)

Intramuscular adrenaline is the first-line treatment [1] for anaphylactic reactions. Adrenaline (epinephrine) is a naturally occurring catecholamine secreted by the adrenal medulla in response to exertion or stress. It is a sympathomimetic amine which is a potent stimulant of both alpha and beta adrenergic receptors and its effects on target organs are, therefore, complex. Adrenaline is the drug of choice to provide rapid relief of hypersensitivity reactions to allergies or to idiopathic or exercise induced anaphylaxis.[2]

Adrenaline (epinephrine) has a strong vasoconstrictor action through alpha adrenergic stimulation. This activity counteracts the vasodilatation and increased vascular permeability leading to loss of intravascular fluid and subsequent hypotension, which are the major pharmacotoxicological features in anaphylactic shock. Through its stimulation of bronchial beta adrenergic receptors, adrenaline (epinephrine) has a powerful bronchodilator action which alleviates wheezing and dyspnoea. Adrenaline (epinephrine) also alleviates pruritus, urticaria and angioedema associated with anaphylaxis.[2]

Anapen Posology and method of administration [2]

The patient should always carry 2 units of auto injectors in case the first administration fails or if one dose is not sufficient.

Posology

The effective dose is typically in the range 0.005-0.01 mg/kg but higher doses may be necessary in some cases. Use in adults: The usual dose is 300 micrograms. Larger adults may require more than one injection to reverse the effect of an allergic reaction. In the absence of clinical improvement or if deterioration occurs, a second injection with an additional Anapen may be administered 5–15 minutes after the first injection. It is recommended that patients are prescribed two Anapen which they should carry at all times. Use in children: The appropriate dose may be 150 micrograms (Anapen Junior) or 300 micrograms (Anapen) of adrenaline (epinephrine), depending on the body weight of the child and the discretion of the doctor. Children and adolescents over 30 kg in weight should be prescribed Anapen 300 micrograms. The auto-injector of Anapen Junior is designed to deliver a single dose of 150 micrograms adrenaline (epinephrine), a dosage below 150 micrograms cannot be administered in sufficient accuracy in children weighing less than 15 kg and use is therefore not recommended unless in a life-threatening situation and under medical advice.

Administration

For intramuscular route only. Anapen consists of a pre-filled syringe of adrenaline (epinephrine) contained in an auto-injection device. The whole is referred to as an auto-injector. One Anapen injection should be administered intramuscularly immediately on the appearance of the signs and symptoms of anaphylactic shock. These may occur within minutes of exposure to the allergen and are most commonly manifested by urticaria, flushing or angioedema; more severe reactions involve the circulatory and respiratory systems. Inject Anapen only into the anterolateral aspect of the thigh, not the buttock. The injected area may be lightly massaged for 10 seconds following injection to accelerate absorption. The auto-injector is designed to inject through clothing or directly through the skin. Anapen auto-injector is intended for immediate self administration by a person with a history of anaphylaxis and is designed to deliver a single dose of 300 micrograms (0.3 ml) adrenaline (epinephrine). For stability reasons 0.75 ml is left in the syringe after use but the unit cannot be used again and should be safely discarded.   The patient/carer should be informed that following each use of Anapen:
  • They should call for immediate medical assistance, ask for an ambulance and state ‘anaphylaxis’ even if symptoms appear to be improving (see section 4.4 of the SPC) 
  • Conscious patients should preferably lie flat with feet elevated but sit up if they have breathing difficulties. Unconscious patients should be placed on their side in the recovery 
  • The patient should if possible remain with another person until medical assistance arrives.

Anapen Contraindications

Hypersensitivity to adrenaline (epinephrine) or to any of the excipients listed in section 6.1 (see section 4.4 for further information on sodium metabisulfite). There are no absolute contraindications for use in allergic emergency situations.

Anapen Special warnings and precautions for use

  • Anapen contains sodium metabisulfite which can cause allergic-type reactions including anaphylactic symptoms and bronchospasm in susceptible people, especially those with a history of asthma. Patients with these conditions must be carefully instructed in regard to the circumstances under which Anapen should be used.
 
  • All patients who are prescribed Anapen should be thoroughly instructed to understand the indications for the use and the correct method of administration (see section 6.6). It is strongly advised also to educate the patient’s immediate associates (e.g. parents, caregivers, teachers) for the correct usage of Anapen in case support is needed in the emergency situation.
 
  • Anapen is indicated as emergency supportive therapy only and patients should be advised to seek immediate medical attention following administration, in order to have close monitoring of the anaphylactic episode and further treatment as required.
 
  • The patient/carer should be informed about the possibility of biphasic anaphylaxis which is characterised by initial resolution followed by recurrence of symptoms some hours later.
 
  • Patients with concomitant asthma may be at increased risk of a severe anaphylactic reaction.
 
  • Use with caution in patients with heart disease e.g coronary heart and cardiac muscle diseases (angina may be induced), cor pulmonale, cardiac arrythmias or tachycardia. There is a risk of adverse reactions following adrenaline (epinephrine) administration in patients with hyperthyroidism, cardiovascular disease (severe angina pectoris, obstructive cardiomyopathy and ventricular arrhythmia and hypertension), phaeochromocytoma, high intraocular pressure, severe renal impairment, prostatic adenoma leading to residual urine, hypercalcemia, hypokalemia, diabetes, or in elderly or pregnant patients. Repeated local injection can result in necrosis at sites of injection from vascular constriction. Accidental intravascular injection may result in cerebral haemorrhage due to a sudden rise in blood pressure. Accidental injection into hands or feet may cause loss of blood flow to adjacent areas due to vasoconstriction.
 
  • Anapen contains less than 1 mmol sodium (23 mg) per dose, i.e. essentially sodium free.
 
  • Patients should be warned regarding related allergens and should be investigated whenever possible so that their specific allergens can be characterised.

PLEASE SEE THE ANAPEN SPC FOR FURTHER INFORMATION 

   
  1. Simons FER. et al. WAO Journal, 2011;4:13-37 Simons FER et al, WAO Guidelines for Assessment and Management of Anaphylaxis,2011
  2. Anapen 300mcg SmPC IEANA300SPC
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