Indications
Epinephrine (also called adrenaline) is a natural hormone and medicine with several uses. It is the first treatment for severe allergic reactions (anaphylaxis), it is used in resuscitation when the heart has stopped, and small amounts are added to local anaesthetic injections, such as Lidocaine used by dentists and surgeons, to make the numbness last longer and reduce bleeding. It is also used in some nebulised and topical forms in hospital, for example for croup or to control bleeding.
How It Works
Epinephrine acts on alpha and beta adrenergic receptors in the body. It narrows small blood vessels, which raises blood pressure, reduces swelling and slows the spread of a local anaesthetic away from the injection site. It also opens the airways, makes the heart beat faster and stronger and blocks the release of allergy chemicals.
Dosage and Administration
The dose depends on the use and is given as prescribed. In local anaesthetic injections it is given by a dentist, doctor or trained health professional. In hospital emergencies and resuscitation it is given by doctors and nurses. People at risk of anaphylaxis may be prescribed an adrenaline auto-injector to inject into the outer thigh in an emergency; they should be trained in its use and must still call for emergency help straight away after using it.
Interactions
- Non-selective beta blockers (such as Propranolol): may cause a sharp rise in blood pressure and slow heartbeat, and make anaphylaxis harder to treat.
- Tricyclic antidepressants (such as Amitriptyline) and MAO inhibitors: stronger effects on blood pressure and heart.
- Halothane and some other anaesthetic gases: risk of irregular heartbeat.
- Digoxin and Quinidine: increased risk of heart rhythm problems.
- Medicines for diabetes: epinephrine raises blood sugar.
Contraindications
In a life-threatening allergic reaction there is no absolute reason not to use epinephrine. For planned uses, such as local anaesthetic with epinephrine, the doctor or dentist may avoid it in people with uncontrolled high blood pressure, severe heart disease, some irregular heart rhythms, an overactive thyroid, narrow-angle glaucoma, or for injection into fingers, toes, ears, nose or penis where blood supply could be cut off.
Side Effects
- Fast or pounding heartbeat, shakiness, anxiety and sweating.
- Headache, dizziness, pale skin.
- Raised blood pressure and blood sugar.
- Nausea or vomiting.
Get urgent medical help for chest pain, a very fast or irregular heartbeat, a severe headache, breathing difficulty, or if allergy symptoms return after using an auto-injector.
Pregnancy and Lactation
In an emergency such as anaphylaxis, epinephrine should be used in pregnancy because the risk of not treating is greater. Small amounts in dental and local anaesthetic injections are generally considered acceptable in pregnancy and breastfeeding. Tell the dentist or doctor if you are pregnant or breastfeeding.
Precautions and Warnings
Tell your doctor or dentist if you have heart disease, high blood pressure, an overactive thyroid, diabetes, glaucoma or Parkinson’s disease, or if you are elderly. Auto-injector users should carry it at all times, check its expiry date and avoid injecting into the hands or feet. After any use for anaphylaxis, hospital observation is needed because symptoms can come back.
Overdose
Too much can cause dangerously high blood pressure, irregular heartbeat, fluid on the lungs and stroke. It is treated as an emergency in hospital.
Therapeutic Class
Sympathomimetic (adrenergic agonist); vasoconstrictor.
Storage
Store below 30°C (or below 25°C if the pack says so), protected from light, do not freeze, and out of the reach of children. Do not use if the solution is discoloured or contains particles.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.