A Drug Safety Update (DSU) issued by MHRA in 2017 includes updated guidance on the use of adrenaline auto-injectors (AAIs) in the management of patients with severe allergies. The DSU provides key advice for both healthcare professionals and patients including:

Key advice for healthcare professionals:

• Prescribe all patients two AAIs.
• Ensure all patients are advised to carry both AAIs at all times.
• Patients with allergies and their carers should be trained to use the specific AAI that they have been prescribed as injection technique varies between different AAIs.
• Patients with allergies and their carers should be encouraged to obtain and practice using a trainer device. Trainer devices (AAIs without needles) are available free of charge from the manufacturer websites (see where to order at the end of this article).

Advice to give to patients with allergies and their carers

All patients and their carers should be provided with the following advice regarding using the AAI:

• Use the AAI at the first sign of an allergic reaction.
• Once you have used the AAI you should:
  • Call 999, ask for ambulance and state “anaphylaxis”, even if your symptoms are improving.
  • Lie flat with your legs raised to maintain blood flow. However if you are having difficulty breathing you may need to sit up to make your breathing easier.
  • Seek help immediately, and if possible make someone stay with you until the ambulance arrives.
  • If you do not start to feel better use the second injector 5-15 minutes after the first one.

All patients prescribed an AAI are advised to carry two devices at all times. This is particularly important for patients with allergic asthma as they are more likely to suffer a severe anaphylactic reaction

This updated advice follows a European Medicines Agency review of AAI following concerns that some devices may administer the adrenaline subcutaneously rather than intramuscularly.

In order for adrenaline to be effective it is important for it to be administered intramuscularly; subcutaneous administration can result in a slower rate of absorption, lower peak adrenaline plasma concentrations and reduced or sub therapeutic effect.

Factors that may affect whether adrenaline is delivered into a muscle include:

• needle length,
• thickness of subcutaneous fat which determines the skin to muscle depth (STMD),
• how the device works, specifically whether the auto-injector is spring loaded or not,
• the angle the device is placed on the skin,
• the force used to activate the device.

Where it is possible that a patient will have a larger STMD, for example obesity, it may be advisable to supply an AAI with a longer needle. The Summary of Product Characteristics (SPC) includes details of the needle length; this information is also included in the following table comparing the key features of the individual AAI:

Training - In all cases pharmacists should ensure that the patient and their carers are shown how to use their AAI. Pharmacists can also signpost the manufacturers’ website as each manufacturer provides training on the use of their specific device for patients and healthcare professionals. 

Trainer devices can be ordered directly from the manufacturers to enable pharmacists to demonstrate how to use an AAI. Patients and their carers should also be encouraged to order a trainer pen so that they can practice using the device.

Pharmacists can give patients the following advice sheet to reinforce the advice provided on how and when to use their AAI. assets.publishing.service.gov.uk/media/54730805ed915d1380000045/con418524.pdf

Further information can be obtained from the individual manufacturer's websites:

• Emerade
  
• Epipen
• Jext