Before diving into the meet of medications best for allergy we need to know what exactly allergy is and mechanism by which its caused.
Allergic:
Rhinitis is the inflammation of mucous membrane of nose and characterized by sneezing, itchy nose\ eyes, watery rhinorrhea, nasal congestion and sometimes a non productive cough.
Mechanism:
Foreign material interacts with mast cells coated with IgE generated in response to previous allergen exposure. Mast cells release mediators as histamines, leukotriens, and chemotactic factors that promote bronchiolar spasm and mucosal thickening.
Drugs prescribed for allergic rhinitis:
Best antiallergic drugs to be used are:
- Antihistamines
- Corticosteroids
- Cromolyn
- Ipratropium
- Decongestants
Antihistamines:
Antihistamines are useful for management of symptoms of allergic rhinitis caused by histamine release. They are more effective for the prevention of symptoms, rather than treatment once symptoms have begun.
Available in the form of eye nasal or opthalmic drug delivery system.
Over the counter drugs
- Cetirizine (zyrtec),
- Fexofenadine (allegra),
- Levocetirizine (xyzal)
- Loratadine (alavert)
- Diphenhydramine (benadryl)
- Older antihistamines may cause drowsiness and sedations slightly. Newer second generation drugs are available over the counter which are non sedating.
Decongestants:
These are often prescribed along with antihistamines. They are short acting alpha adrenergic agonists used to constrict dilated arterioles in nasal mucosa and reduce airway resistance, relieve congestion. They come in nasal spray, eye drops, liquid, or pill form.
- Nasal sprays should not be should for long term cure as it can cause rebound congestion and worsen the symptoms.
Over the counter drugs:
- Pseudoephedrine (sudafed)
- Phenylephrine (neo sudafed)
- Oxymetazoline (afrin)
- Decongestants raise blood pressure, insomnia and urinary flow is restricted.
Corticosteroids:
Steroids are used to relieve the inflammation associated with allergies. They are also used to treat and prevent nasal stuffiness, sneezing, itchy nose throat and eyes due to hayfever also caising reduced inflammation of mucous membranes.
- Over the counter nasal steroids:
- Budesonide (rhinocort)
- Fluticasone( flonase)
- Triamcinolone (nasocort)
Eye drops:
- Dexamethasone opthalmic.
- Systemic absorption is minimal and side effects are localized causing nasal irritation, nosebleed, sore throat, candidiasis. Hence thses should not b inhaled deeply.
Cromolyn:
Intranasal cromolyn is useful in allergic rhinitis particularly when administered before contact with allergen. To optomize effects should begin at least 1to 2 weeks prior to allergen exposure.
Over the counter drugs:
- Cromolyn (nasalcrom).
Ipratropium:
Intranasal formulation available to treat rhinorrhea associated with allergic rhinitis or common cold. But does not relieve sneezing or nasal congestion.
Over the counter drug:
- Ipratropium( atrovent).
