Seasonal Allergies: Antihistamines & the Future Jacquelyn Covarrubias CHEM 5389 April 24, 2007

Outline 1.What is an Allergy? 2.Allergens 3.Allergic Rhinitis 4.Histamine and Mast Cells 5.Symptoms 6.Common Structures of Antihistamines 7.Treatments 8.Future Ideas for Dealing with Allergies

What is an allergy?  Allergies are caused by an over-sensitive immune response. The immune system normally protects the body against harmful substances. Allergy symptoms occurs when the immune system reacts to allergens that are generally harmless and in most people do not cause an immune response.  When a person with allergies breathes in an allergen such as pollen or dust, antibodies are produced. Immunoglobulin E is a class of immunoglobulins that includes the antibodies elicited by an allergen. A person who has an allergy usually has elevated blood levels of IgE. IgE antibodies attack and engage the invading army of allergens.  When the antibodies are stimulated by pollen and dust, histamine and other chemicals are released. This causes itching, swelling, and mucus production. Symptoms vary from person to person.

Common Allergens  Airborne particles (hay fever) – Grass, weeds, timothy grass, birch trees, and Mold spores  Drugs –Penicillin, sulfonamides, salicylates, local anesthetics, and latex  Insect stings –bee sting venom and wasp sting venom  Animal products (animal allergy) – Animal hair and dander, cockroach calyx, and dust mite excretion  Foods (food allergy) –Peanuts, nuts, sesame, pittster fruit, seafood eggs, peas, beans, soybeans, celery, soy, milk, wheat, and corn

Allergic Rhinitis  Allergic rhinitis is the fifth most prevalent chronic disease in the United States, affecting up to 40 million adults and children each year.  Allergic rhinitis costs the nation approximately $5.3 billion in direct and indirect costs (including time lost from work and school) and accounts for about 10,000 absences from school.

Histamine and Mast Cells  When you are exposed to an allergen, a specific type of white blood cell called the mast cell, which is located in the membrane lining the nose and sinuses, releases a chemical called histamine. Histamine attaches to its site of action called receptors on nearby blood vessels, causing them to dilate or enlarge, leading to redness, swelling, itching, and changes in the secretions.

Histamine and Mast Cells Histamine: Mast Cells:

Symptoms  Nose: swelling of the nasal mucosa (allergic rhinitis)  Eyes: redness and itching (allergic conjunctivitis)  Airways: bronchoconstriction, wheezing, itchy or sore throat, post nasal drip, and cough  Ears: feeling of fullness, possibly pain, and impaired hearing due to the lack of eustachian tube drainage.

Common Structures of Antihistamines Amino alkyl ethers Bromodiphenhydramine: Diphenhydramine hydrochloride Diphenhydramine hydrochloride:Carbinoxamine: Benadryl (diphenhydramine hydrochloride) will be discussed later.

Common Structures of Antihistamines Substituted alkylamines Brompheniramine: Chlorphenamine: Pheniramine maleate Pheniramine maleate: These antihistamines will not be discussed later.

Common Structures of Antihistamines Substituted ethylene diamines Methapyrilene:Chloropyramine:Pyribenzamine: These first generation antihistamines are hardly used anymore and will not be discussed further.

Common Structures of Antihistamines Phenothiazine derivatives Mequitazine: Methdilazine: Promethazine: These antihistamines will not be discussed later.

Common Structures of Antihistamines Piperazine derivatives Cetirizine hydrochloride: Niaprazine: Buclizine: Zyrtec (cetirizine hydrochloride) will be discussed later.

Common Structures of Antihistamines Tricyclic derivatives Desloratadine: Loratadine:Ketotifen: Clarinex (desloratadine) and Claritin (loratadine) will be discussed later.

Common Structures of Antihistamines Antiallergic agents excluding corticosteroids Antazoline: Azelastine hydrochloride: Fexofenadine hydrochloride: Astelin (azelastine hydrochloride) and Allegra (fexofenadine hydrochloride) will be discussed later.

Treatments: Benadryl  Diphenhydramine is a first generation antihistamine drug.  It works by blocking the effect of histamine at H1 receptor sites. This results in effects such as the reduction of smooth muscle contraction, making diphenhydramine a popular choice for treatment of the symptoms of allergic rhinitis, hives, motion sickness, and insect bites and stings.  Side effects include: drowsiness, possibilities of motor impairment, dry mouth and throat, flushed skin, rapid or irregular heartbeat, blurred vision at near point, abnormal sensitivity to bright light, pupil dilatation, urinary retention, constipation, difficulty concentrating, short-term memory loss, visual disturbances, hallucinations, confusion, erectile dysfunction, and delirium. Diphenhydramine hydrochloride Diphenhydramine hydrochloride:

Treatments: Allegra Fexofenadine hydrochloride is a second-generation antihistamine, which does not cross the blood-brain barrier, and so causes less drowsiness than first- generation histamine- receptor antagonists.Fexofenadine hydrochloride is a second-generation antihistamine, which does not cross the blood-brain barrier, and so causes less drowsiness than first- generation histamine- receptor antagonists.  Fexofenadine hydrochloride is a histamine H1-receptor antagonist.  Treats sneezing, rhinorrhea, itchy nose/palate/throat, and itchy/watery/red eyes.  Common side effects: nausea, vomiting, weakness, drowsiness, sleepiness, and depression Fexofenadine hydrochloride:

Treatments: Clarinex  Desloratadine is a tricyclic antihistamine, which has a selective and peripheral H1- antagonist action. It has a long- lasting effect and does not cause drowsiness because it does not readily enter the central nervous system.  Clarinex treats sneezing, runny nose, itching and watering of the eyes, and other allergic symptoms.  Common Side Effects: sore throat, dry mouth, drowsiness, fatigue, headache, and gastrointestinal disturbances. Desloratadine:

Treatments: Claritin  Loratadine is a tricyclic antihistamine, which has a selective and peripheral H1- antagonist action. It has a long-lasting effect and does not normally cause drowsiness because it does not readily enter the central nervous system.  Loratadine treats watery eyes, runny nose, itching eyes, and sneezing. It may also be used to treat hives.  Common Side Effects: dry mouth, headache and gastrointestinal disturbances. Loratadine:

Treatments: Zyrtec  Cetirizine hydrochloride is a racemic selective H1 receptor antagonist.  Cetirizine hydrochloride treats itchy, red, and watery eyes, sneezing, runny, and itchy nose, postnasal drip and itching from hives.  Common side effects: sleepiness, fatigue, or dizziness, headache, and dry mouth. Cetirizine hydrochloride:

Treatments: Astelin  Azelastine hydrochloride is the only prescription antihistamine approved to treat nasal congestion.  It is a steroid free and pseudoephedrine free antihistamine nasal spray which provides relief from congestion, itchy or runny nose, sneezing, and postnasal drip. Astelin, the Azelastine hydrochloride brand name, blocks the effects of histamine.  The medicine is a nasal spray which enables quicker relief from allergy symptoms.  Astelin is unique because it treats symptoms caused by both allergens and irritants.  Because Astelin does not contain a topical vasoconstrictor like other nasal decongestants, it does not cause chronic nasal stuffiness.  Common side effects: bitter taste, headache, nasal inflammation or burning, and drowsiness. Azelastine hydrochloride:

Future Ideas  According to the American Academy of Allergy, Asthma and Immunology, 30 million Americans suffer from some form of cat allergy.  Allerca has produced the world's first hypo- allergenic cats. They allow people with feline allergies to enjoy having a pet without having allergic symptoms.

Allerca Cats  The hypo-allergenic cats are made by focusing in on the cat allergen that causes the symptoms.  Normally, the cat allergen can remain airborne for several months and is ten times smaller than pollen or dust particles.  There is a glycoprotein secreted by the cat's skin and salivary glands whose production depends on the Fel d 1 gene.  The company altered the protein to allow the cat to secrete a genetic divergent Fel d 1 that does not trigger symptoms of allergies and is not harmful to the cat. The cats were tested on people with cat allergies and proved that these new cats did not cause any symptoms.

Only $9895!!  ALLERCA began deliveries of GD kittens to eager customers at the end of  You too can now own an ALLERCA GD kitten. The price is $6950 per kitten. Orders made on or before May 1, 2007 qualify for the initial price of $3950.  A processing and transportation fee of $995 is due eight weeks prior to delivery.  The Premium Placement fee is $ 1,950 to guarantee your delivery in 1 year rather than 2 years.

Overview How Allergies Occur: How to treat Allergies according to symptoms: