Jext Auto-Injector

What is Jext?

Jext is a pre-filled auto-injector containing a sterile solution of adrenaline (also known as epinephrine). It belongs to a class of drugs called sympathomimetic amines (alpha and beta adrenergic agonists). In the UK, medicines like Jext are classified as Prescription-Only Medicines (POMs)[citation:4].

Mechanism of Action

Adrenaline is a natural hormone and neurotransmitter that your body releases during "fight or flight" responses. During anaphylaxis, it works through several crucial mechanisms[citation:6]:

• Constricts Blood Vessels (Vasoconstriction): Reverses dangerous drops in blood pressure and reduces swelling (especially in the throat and face).
• Relaxes Airways (Bronchodilation): Opens up the airways, making breathing easier.
• Increases Heart Rate & Strength: Supports blood circulation.
• Suppresses Further Allergic Mediator Release: Helps stop the cascade of inflammatory chemicals.

Analogy: Think of anaphylaxis as your body's immune system massively overreacting and causing systemic chaos. Jext delivers adrenaline like an emergency fire brigade – it doesn't remove the original spark (the allergen), but it directly counters the life-threatening effects, giving you vital time to get to hospital.

What is Jext Used For?

Jext is indicated for the emergency treatment of acute, life-threatening allergic reactions (anaphylaxis).

Anaphylaxis is a severe, potentially life-threatening allergic reaction that can develop rapidly[citation:6]. It should always be treated as a medical emergency.

Before Using Jext

Jext is prescribed after a specialist allergy assessment. Your doctor will ensure you have a formal anaphylaxis management plan. Before prescribing, they will review:

• Confirmed Allergy Diagnosis: Evidence of severe allergic reaction or positive allergy tests.
• Medical History: Heart disease, high blood pressure, overactive thyroid (hyperthyroidism), diabetes, glaucoma, adrenal gland tumour (phaeochromocytoma).
• Current Medications: To check for drug interactions.
• Body Weight: To determine correct strength (150 mcg or 300 mcg).

Training is Mandatory: You, your family, carers, and school staff (if a child) must receive proper training. Practice with a Jext Trainer device (contains no needle or drug) is essential[citation:2][citation:3].

Jext Contraindications

Critical Note: In a genuine life-threatening anaphylactic emergency, there are NO absolute contraindications. The risk of death from anaphylaxis outweighs the risks of adrenaline administration. USE JEXT FIRST.

Special Population Considerations

Elderly (65+)

• May be more susceptible to adrenaline's effects on the heart and blood pressure (increased risk of angina, arrhythmia). Dose remains based on weight. Use with caution.

Paediatric Patients

• Jext 150 mcg is for children weighing 15-30 kg. Jext is not recommended for children under 15 kg.
• Growth and weight should be monitored regularly, and the dose adjusted accordingly.
• The British Society for Allergy & Clinical Immunology (BSACI) provides specific Paediatric Allergy Action Plans for children at risk, which should be completed by a health professional[citation:5].

Jext and Other Medicines

Inform all doctors about ALL medications you take. Significant interactions include:

• Antidepressants: Tricyclics (e.g., amitriptyline) & MAOIs (e.g., phenelzine) – can potentiate adrenaline effects, risking severe hypertension.
• Parkinson's Drugs: COMT inhibitors (e.g., entacapone), levodopa – may increase heart rate and arrhythmia risk.
• Heart Medications: Digoxin, quinidine – increase risk of irregular heart rhythms.
• Beta-Blockers (e.g., propranolol): May blunt adrenaline's effect and paradoxically worsen anaphylaxis; can also cause severe hypertension.

Pregnancy & Breastfeeding

Pregnancy

• Data on adrenaline use in pregnancy is limited. However, in an anaphylactic emergency, Jext MUST BE USED. The life-threatening risk to both mother and fetus from untreated anaphylaxis far outweighs any potential risk from adrenaline. Do not hesitate.
• If conscious and pregnant, lie on your left side after using Jext[citation:6].

Breastfeeding

• Adrenaline is unlikely to be excreted in breast milk in significant amounts after a single emergency dose. The benefit of treating anaphylaxis outweighs any potential risk to the infant.

Driving & Machine Operation

• The adrenaline injection itself is unlikely to impair driving. However, the anaphylactic reaction WILL impair your ability to drive or operate machinery.
• Do NOT drive after using Jext. You must be assessed in hospital. The effects of anaphylaxis (and adrenaline) like dizziness, tremor, and weakness can be significant.

Jext Ingredients

Active Substance

• Adrenaline (as tartrate). 1 mg/mL solution.

Excipients (Other Ingredients)

Sodium Content: Less than 1 mmol (23 mg) per dose – essentially 'sodium-free'.

How to Use Jext

Jext is for emergency intramuscular use ONLY in the outer thigh. It can be injected through clothing if necessary, but not through thick clothing like denim[citation:3]. NEVER inject into buttocks, hands, feet, or veins.

Core Principle: IF IN DOUBT, USE IT. Do not delay. Early administration is critical for survival[citation:7].

Jext Dosage Guidelines

Repeat Dosing: A single dose may not be enough. If symptoms have not improved within 5 to 10 minutes, use a second Jext in the opposite thigh[citation:3][citation:6]. This is why doctors prescribe at least two pens to carry at all times.

Administration Instructions

Step-by-Step Emergency Use[citation:3]:

1. GRASP: Hold the Jext pen in your dominant hand, with your thumb nearest the yellow cap. Do not cover the black tip.
2. PULL: With your other hand, pull off the yellow safety cap straight off.
3. PLACE: Place the black tip firmly against the outer part of the thigh. Hold at a 90° angle.
4. PUSH & HOLD: Push down hard until you hear a loud "CLICK". Hold firmly in place for at least 10 FULL SECONDS.
5. REMOVE & MASSAGE: Remove the pen. The black tip extends to cover the needle. Massage the injection area for 10 seconds.
6. CALL 999: DIAL 999 IMMEDIATELY. Ask for an ambulance and state "ANAPHYLAXIS". Lie down with legs raised (if breathing allows).

Visual Check: After use, a coloured plastic rod (white for 300 mcg, blue for 150 mcg) will appear in the inspection window, confirming activation[citation:3].

Missed Dose Management

Not applicable. Jext is not a scheduled medication; it is used only in response to an anaphylactic emergency. The concept of a "missed dose" does not apply. The critical action is to use it as soon as anaphylaxis is suspected.

Overdose Information

Overdose can occur from accidental injection (e.g., into a finger) or from using multiple doses unnecessarily.

Symptoms of Adrenaline Overdose

• Severe, sudden increase in blood pressure
• Irregular, rapid, or pounding heartbeat (palpitations, arrhythmias)
• Extreme anxiety, tremor, headache

Action

Seek IMMEDIATE medical help (A&E). Treatment is supportive. Inform the hospital you have received an adrenaline injection.

Accidental Injection into Hand/Foot: Go to A&E immediately for assessment of blood supply to the digit.

Possible Side Effects

Side effects are common due to adrenaline's powerful effects but are generally temporary and less dangerous than untreated anaphylaxis.

*Specific frequencies from clinical trials are not well-defined for emergency use.

How to Store Jext

Storage Guidelines

• Keep in the provided plastic carry case to protect it.
• Store below 25°C. Do not refrigerate or freeze.
• Keep out of sight and reach of children.
• Check the solution regularly through the inspection window. It must be clear, colourless, and particle-free. Replace if discoloured[citation:3].
• Do not use after the expiry date (EXP) on the carton. You can register for expiry alerts on the manufacturer's website[citation:2][citation:3].

Disposal

• After use, give the used pen to ambulance crew or medical staff for safe disposal. The needle is automatically shielded[citation:3].
• Do not dispose of in household waste.

Pack Information

Pack Sizes

• Single pack with 1 pre-filled auto-injector.
• Multipack with 2 pre-filled auto-injectors.

Components

• Pre-filled glass cartridge auto-injector.
• Plastic carry case.
• Instructions for use.

Marketing Authorisation

• Holder: ALK-Abelló A/S, Denmark.
• This medicine has a valid marketing authorisation in the UK[citation:1].

Where Can I Buy Jext Online in the UK