Anti-allergic drugs are used to mitigate or impede the manifestation of allergic reactions such as severe bronchial asthma, allergic rhinitis, mastocytosis and exercise-induced bronchospasm.
How is allergy caused?
When a person comes in contact with the allergy-causing substance for the first time, he/she might not develop an allergic reaction straight away. The immune system memorizes the allergen and prepares antibodies. When the individual experiences second exposure, the immune system briskly recognizes the allergen and attacks it with ease. This process of antibody pre-accumulation is called sensitization.
Hypersensitivity of an individual’s immune system to certain foreign materials or substances like foods, bee venom, pollen, mites, moulds, dust, ticks, pet fur, insects and medications trigger an allergic response. These substances or foreign materials are termed allergens.
Hypersensitive immune response to an allergen is known as atopy; it is IgE mediated and causes a genetic predisposition that augments allergic diseases such as asthma, atopic dermatitis(eczema) and allergic rhinitis.
Atopy can also be triggered by allergic irritants like detergents, soaps, shampoo, bubble baths and environmental allergens(weather change–cold, dry and humidity).
Symptoms of allergy
Allergic symptoms can be of two types: localized and systemic.
Localized symptoms may include:
- Swelling can be observed in nasal mucosa(Allergic Rhinitis).
- Itching and redness in the conjunctiva(Allergic Conjunctivitis).
- Dyspnoea, wheezing, bronchoconstriction and anaphylaxis(a severe form of allergy).
- Ear fullness, pain in ears and impaired hearing.
- Skin rashes(eczema, hives), urticaria and contact dermatitis.
Systemic symptoms may include:
- The circulatory system, digestive system and respiratory system can be affected.
- Cutaneous reactions, oedema, hypotension, coma, bronchoconstriction and even death.
Types of allergy
Allergic reactions were classified into four types by two British immunologists namely: Robert Coombs and Philip Gell, in the year 1963. The four types are as follows:
- The time required for the onset of symptoms is from a few seconds to minutes.
- In response to allergens such as insect bites, pollen, dust mites, animal dander, or certain foods–the immune system produces IgE antibodies.
- Anaphylactic reactions are classic examples.
- Symptoms are visible after a few minutes to hours.
- IgG and IgM antibodies are produced. These antibodies activate the complement immune system.
- For instance: autoimmune hemolytic anemia.
- Symptoms usually appear after several hours.
- The immune system produces IgG and IgM antibodies. These antibodies react with allergen and form immune complexes.
- For example: Lupus
- It takes some hours to a few days for the symptoms to appear.
- Observed in long-term infectious diseases.
- For example: Tuberculosis.
Diagnosis and treatment for allergy
A workable method for the treatment of allergic reactions is prevention; by avoiding known allergens. Briefing the exact symptoms to a doctor might help to identify the cause or occurrence of the allergic reaction with ease. The doctor may suggest some tests such as blood tests, skin prick tests, basophil activation test(BAT) and patch tests.
Always consider informing the doctor if you are under any herbal/allergy medication, or have diabetes, high blood pressure/osteoporosis and glaucoma. This will help the doctor to understand better about your allergic condition and provide you with an appropriate prescription.
Avoiding allergens is not always possible. Under such circumstances, medical treatment is advised by the doctor. The drugs for the treatment of allergic reactions are known as anti-allergic drugs.
Anti-allergic drugs or medications are available in various forms such as pills, injections, eye drops, inhalers, skin creams, liquids and nasal sprays.
Anti-allergic drugs suppress the symptoms of allergic reactions by arresting the production and release of chemical messengers that regulate cellular responses. Some traditional anti-allergic drugs such as glucocorticoids, Selective β2-receptor agonists, nedocromil and disodium cromoglycate are known to arrest allergic reactions in various courses of action. Depending on the mode of action anti-allergic drugs can be classified into five types namely:
- Mediator-release inhibitors
- Histamine H1 antagonists
- Thromboxane A2 inhibitors and antagonists
- Leukotriene antagonists
- Th2 cytokine inhibitors
Antihistamine mode of action
An antihistamine drug regulates the release of histamine compounds. Histamines are chemical messengers that influence cellular responses. These compounds attach to blood vessel receptors and enlarge them. Histamines also bind to various receptors and cause swelling, itching, redness and changes in the level of secretions. Antihistamine drugs act on the histamine compounds, halt their attachment to other receptors and prevent allergic symptoms.
Prevention and precautions to avoid allergy
Allergies not by any means can be prevented. Symptoms of allergic reactions can be temporarily relieved though. Individuals experiencing allergic reaction should:
- Take appropriate measures to avoid subjection to known allergens.
- Carry two auto-injectors with usage instructions.
- Consider informing colleagues, friends, relatives and others about the allergy and the appropriate way to use the auto-injector.
- Ponder about wearing a medical-identification bracelet briefing about the allergy.