Drugs For Anaphylaxis

3 Drugs Used in Anaphylaxis

The main drug used in anaphylaxis is adrenaline (usually given as an auto-injector). It acts very quickly to improve blood flow, reduce oedema and increase heart rate and strength of contraction.

It should always be given first to anyone who has a known allergy to food, insect sting or medication. It is also important that they are referred to an allergist/immunologist for testing and ongoing management of their allergies.

Epinephrine

Epinephrine is a hormone that is produced naturally in the adrenal glands and is part of the body’s “fight or flight” response to stress. It’s also a medication that can be used to treat life-threatening allergic reactions called anaphylaxis. It is injected into the mid-outer thigh (vastus lateralis muscle) in an emergency situation and can save lives if given within minutes of the onset of severe allergic symptoms. It works by stimulating alpha- and beta-adrenergic receptors in the heart, lungs, liver, and blood vessels. It acts as a vasoconstrictor, counteracting the vascular leakage and loss of intravascular fluid that leads to hypotension in anaphylactic shock. It also has bronchodilator effects and alleviates pruritus, urticaria, and angioedema.

It should be administered by injection only in anaphylaxis and only under the guidance of a physician. Ask your allergist-immunologist to show you and your family members how to use an epinephrine auto-injector and make sure you have at least two — one for yourself and one for someone else who may need it in an emergency.

Salbutamol

Usually prescribed for asthma and chronic obstructive pulmonary disease (COPD, eg bronchitis and emphysema), salbutamol helps to open up the airways in the lungs making it easier to breathe. It can be taken by mouth or through a device called a nebuliser which allows the medicine to be delivered directly into the lungs. This is a safer option as it minimises the amount of the drug that can be absorbed into other parts of the body such as the heart.

In the fatality series described above, only 14 percent of those who died from anaphylaxis received epinephrine before respiratory or cardiac arrest [1]. Therefore, prompt assessment and treatment is important.

Epinephrine should be used as the first line of treatment for anaphylaxis. It is available as an injection and auto-injector. It is essential that the correct dilution is used when administering this medication.

Chlorpheniramine

Chlorpheniramine is an antihistamine that works by blocking the effects of the natural chemical histamine in the body. It relieves sneezing; itching of the nose, throat, or eyes; and watery, runny eyes or nose caused by allergies, the common cold, or hay fever. It also reduces the itching of the nose or throat associated with a severe allergic reaction (anaphylaxis).

It is in a class of medications called alkylamine first-generation H1 antagonist antihistamines. It works by blocking the action of histamine, which is produced when immune system cells respond to allergens and cause a chain reaction that leads to cell-degranulation and release of histamine and other chemicals. Histamine then acts on histamine receptors and produces a variety of symptoms, such as pruritis, vasodilatation, flushing, hypotension, headache, tachycardia, and bronchoconstriction.

Use this medication only as directed on the label, and tell your doctor if you have any questions. This medicine is not for long-term use. Overdose may lead to severe and possibly fatal side effects.

Antihistamines

A severe allergic reaction can cause you to go into shock. This is a life-threatening emergency and needs immediate medical attention. The first drug you need to give is epinephrine, which is given with a self-injecting syringe or needle device (auto-injector). Epinephrine should be used immediately at the first sign of anaphylaxis. It is the only medication proven to stop this severe reaction.

Antihistamines block the effects of histamine, a chemical that is released during an allergic reaction. They are available in tablet, capsule, chewable and liquid forms and can be bought over the counter or on prescription from a doctor. Some can be taken while pregnant or breastfeeding, but check the leaflet that comes with them before taking.

H1 antihistamines are effective for relieving itching and urticaria, but they do not relieve stridor, wheezing, gastrointestinal symptoms and signs, hypotension or shock. It is important that epinephrine is administered as soon as anaphylaxis is recognised or suspected, even if formal diagnostic criteria are not met, because delayed administration has been associated with fatalities [1]. [1]

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