Clinical Pharmacy in Clinical Pharmacy in Allergology Allergology

AllergiesAllergies AllergicAllergic RhinitisRhinitis ('hay fever') ('hay fever') AsthmaAsthma Chronic Sinusitis Chronic Sinusitis Eczema (Atopic Dermatitis) Eczema (Atopic Dermatitis) Chronic Hives & Angioedema (swelling) Chronic Hives & Angioedema (swelling) Food Allergies Food Allergies Allergies to Insect Stings Allergies to Insect Stings Contact Dermatitis Contact Dermatitis Less common conditions including Less common conditions including

anaphylaxis, drug allergies anaphylaxis, drug allergies and immune deficiencies. and immune deficiencies.

What Are Allergies? What Are Allergies?

Allergies are a reaction by the Allergies are a reaction by the body's immune system to body's immune system to harmless substances that it sees harmless substances that it sees as harmful.  The allergy causing as harmful.  The allergy causing substances are called allergens.  substances are called allergens.  It is as if the immune system is It is as if the immune system is overly-active in response to overly-active in response to otherwise innocuous substances.otherwise innocuous substances.

TERMS Allergen—A substance that provokes an

allergic response. Anaphylaxis—Increased sensitivity

caused by previous exposure to an allergen that can result in blood vessel dilation (swelling) and smooth muscle contraction. Anaphylaxis can result in sharp blood pressure drops and difficulty breathing.

Antibody—A specific protein produced by the immune system in response to a specific foreign protein or particle called an antigen.

Antigen—A foreign protein to which the body reacts by making antibodies.

Routes:Allergens enter the body through

the airways, the skin, the gastrointestinal tract, and thecirculatory system

SYMPTOMSAirborne allergens cause the sneezing, runny nose,and itchy, bloodshot eyes of hay fever (allergic rhinitis).Airborne allergens can also affect the lining of thelungs, causing asthma, or the conjunctiva of the eyes,causing conjunctivitis (pink eye). Exposure to cockroachallergans have been associated with the developmentof asthma. Airborne allergans from householdpets are another common source of environmentalexposure.

SYMPTOMS

Allergens in food can cause itching and swelling of thelips and throat, cramps, and diarrhea. When absorbedinto the bloodstream, they may cause hives (urticaria)or more severe reactions involving recurrent, noninflammatory swelling of the skin, mucous membranes, organs, and brain (angioedema). Some food allergens may cause anaphylaxis, a potentially life-threatening condition marked by tissue swelling, airwayconstriction, and drop in blood pressure. Allergies to foods such cow’s milk, eggs, nuts, fish, and legumes (peanuts and soybeans) are common. Allergies to fruits and vegetables may also occur.

SYMPTOMS

In contact with the skin, allergens can cause reddening,itching, and blistering, called contact dermatitis.Skin reactions can also occur from allergens introducedthrough the airways or gastrointestinal tract.This type of reaction is known as atopic dermatitis.Dermatitis may arise from an allergic response (suchas from poison ivy), or exposure to an irritant causingnonimmune damage to skin cells (such as soap, cold,and chemical agents).

SYMPTOMS

Injection of allergens, from insect bites and stings or drug administration, can introduce allergens directly into the circulation, where they may cause system-wide responses (including anaphylaxis), as well as the local ones of swelling and irritation at the injection site.

The following types of drugs commonly cause allergic reactions:

• penicillin or other antibiotics

• flu vaccines

• tetanus toxoid vaccine

• gamma globulin

SYMPTOMS (cont’d)

Symptoms depend on the specific type of allergicreaction. Allergic rhinitis is characterized by an itchy,runny nose, often with a scratchy or irritated throat dueto post-nasal drip. Inflammation of the thin membranecovering the eye (allergic conjunctivitis) causes redness,irritation, and increased tearing in the eyes. Asthma causeswheezing, coughing, and shortness of breath.

SYMPTOMS (cont’d)Symptoms of food allergies depend on the tissues most

sensitive to the allergen and whether the allergen spread systemically by the circulatory system. Gastrointestinal

symptoms may include swelling and tingling in the lips,tongue, palate or throat; nausea; cramping; diarrhea; andgas. Contact dermatitis is marked by reddened, itchy,weepy skin blisters, and an eczema that is slow to heal. Itsometimes has a characteritic man-made pattern, such asa glove allergy with clear demarkation on the hands,wrist, and arms where the gloves are worn, or on the

earlobes by wearing earrings.

Skin reactions

Skin reactionsinclude the raised, reddened, and itchy patches calledhives that characteristically blanch with pressure andresolve within twenty-four hours. A deeper and moreextensive skin reaction, involving more extensive fluidcollection and pain, is called angioedema. This usuallyoccurs on the extremities, fingers, toes, and parts of thehead,neck,and face.

Anaphylaxis

Anaphylaxis is marked by airway constriction, blood pressure drop, widespread tissue swelling, heart rhythm abnormalities, and in some cases, loss of consciousness. Other syptoms may include, dizziness,

weakness, seizures, coughing,flushing, or cramping.The symptoms may begin within five minutes afterexposure to the allergan up to one hour or more later.Mast cells in the tissues and basophils in the bloodrelease mediators that give rise to the clinical symptomsof this IgE-mediated hypersensitivity reaction. Commonly,this is associated with allergies to medications, foods,and insect venoms.

Anaphylaxis

In some individuals, anaphylaxis can

occur with exercise, plasma exchange, hemodialysis, reaction to insulin, radocontrast media used in certain types of medical tests. and rarely during the administration of local anesthetics.

The allergic response

TreatmentAvoiding allergens is the first line of defense to reduce the possibility of an allergic attack.

Complete environmental control is often difficult toaccomplish, hence therapuetic interventions maybecome necessary. A large number of prescription andover-the-counter drugs are available for treatment ofimmediate hypersensitivity reactions. Most of thesework by decreasing the ability of histamine to provokesymptoms. Other drugs counteract the effects of histamineby stimulating other systems or reducing immuneresponses in general.

TreatmentANTIHISTAMINES block the histamine

receptors on nasal tissue, decreasing the effect of histamine released by mast cells. They may be used after symptoms appear, though they may be even more effective when used preventively, before symptoms appear. Antihistamines are help reduce sneezing, itching, and rhinorrhea.

TreatmentI generation antihistamines side effect

Drowsinessdry mouth,tachycardia, blurred vision, constipation, lower the threshold for seizures.

diphenhydramine (Benadryl and generics)chlorpheniramine (Chlor-trimeton and generics)brompheniramine (Dimetane and generics)clemastine (Tavist and generics)These medicatios care should be taken when operating motor vehicles

Treatment

Newer antihistamines that do not cause drowsiness or pass the blood-brain barrier are available by prescription and include the following:

• loratidine (Claritin)

• fexofenadine (Allegra)

Treatment MAST CELL STABILIZERS

Cromolyn sodium prevents the release of mast cell granules, thereby preventing the release of histamine and other chemicals contained in them. It acts as a preventive treatment if it is begun several weeks before the onset of the allergy season.

It can also be used for year round allergy prevention. Cromolyn sodium is available as a nasal spray for allergic rhinitis and in aerosol (a suspension of particles in gas) form for asthma.

Treatment LEUKOTRIENE MODIFIERS

These medications are useful for individuals with aspirin sensitivity,sinusitis,

poliposis, urticaria. Examples include zafirlukast (Accolate), montelukast (Singulair), and zileuton (Zyflo).

When zileuton is used, care must be taken to measure liver enzymes.

ALLERGIC RHINITISAllergic rhinitis, more commonly referred to as hay

fever, is an inflammation of the nasal passages caused byallergic reaction to airborne substances.

Allergic rhinitis (AR) is the most common allergic condition and one of the most common of all minor afflictions.There are two types of allergic rhinitis: seasonal and perennial. Seasonal AR occurs in the spring, summer, and early fall, when airborne plant pollens are at their highest levels. In fact, the term hay fever is really a misnomer, since allergy to grass pollen is only one cause of symptoms for most people. Perennial AR occurs all year and is usually caused by home or workplace airborne pollutants. A person can be affected by one or both types. Symptoms of seasonal AR are worst after being outdoors, while symptoms of perennial AR are worst after spending time indoors.

ALLERGIC RHINITIS. Symptoms

Inflammation causes

itching, sneezing, runny nose, redness, and tenderness. Sinus swelling can constrict the eustachian tube that connects the inner ear to the throat, causing a congested feeling and “ear popping.”

The drip of mucus from the sinuses down the back of the throat, combined with increased sensitivity, can also lead to throat irritation and redness. AR usually also causes redness, itching, and watery eyes. Fatigue and headache are also common.

ALLERGIC RHINITIS. TreatmentAvoidance of the allergens is the best treatment,

but this is often not possible. When it is not possible to avoid one or more allergens, there are two major forms of medical treatment, drugs and immunotherapy.

DRUGSANTIHISTAMINES. Antihistamines block the histaminereceptors on nasal tissue, decreasing the effect ofhistamine release by mast cells. They may be used aftersymptoms appear, though they may be even more effectivewhen used preventively, before symptoms appear. Awide variety of antihistamines are available.

Treatment of anaphylaxisThe emergency condition of anaphylaxis is treated with injection of adrenaline (epinephrine).

Paticular care should be taken to assess the affected individual’s airway status, and he or she should be placed in a recumbent pose and vital signs determined.If a reaction resulted from insect sting or an injection, a tourniquet may need to be placed proximal to the area where the agent penetrated the skin. This should then be released at intervals of ten minutes at a time, for one to two minutes duration. Oxygen may be given, as well as intravenous replacement fluids.Antihistamines may be used for skin rash, and aminophylline for bronchial constriction. If the upper airway is obstructed, placement of a breathing tube or tracheostomy tube may be needed.

Immunologic Reactions to Drugs & Immunologic Reactions to Drugs & Drug Allergy Drug Allergy

Immediate (Type I) Drug Allergy,Immediate (Type I) Drug Allergy,

Autoimmune (Type II) Reactions to Drugs, Autoimmune (Type II) Reactions to Drugs,

SSerum Sickness & Vasculitic (Type III) erum Sickness & Vasculitic (Type III) Reactions. Reactions.

Drug hypersensitivityDrug hypersensitivity is defined as an immune- is defined as an immune-mediated response to a drug agent in a sensitized mediated response to a drug agent in a sensitized patient. patient. Drug allergyDrug allergy is restricted specifically to a is restricted specifically to a

reaction mediated by IgE.reaction mediated by IgE. Immune-mediated reactions account for 5 Immune-mediated reactions account for 5 to 10 percent of all drug reactions and to 10 percent of all drug reactions and constitute true drug hypersensitivity, with constitute true drug hypersensitivity, with IgE-mediated drug allergies falling into this IgE-mediated drug allergies falling into this category. category. Type I reactions (IgE-mediated); Type II Type I reactions (IgE-mediated); Type II reactions (cytotoxic); Type III reactions reactions (cytotoxic); Type III reactions (immune complex); and Type IV reactions (immune complex); and Type IV reactions (delayed, cell-mediated). (delayed, cell-mediated).