Drug Therapy to Decrease Histamine Effects and Allergic Response

Allergic Rhinitis

1st exposure to antigen leads to forming IgE molecules, bind to surface membranes of mast cells, sensitizes mast cells to the effects of inhaled antigens when sensitized mast cells are re-exposed 2nd exposure to inhaled pollen's or other antigens they release histamine and other chemical mediators which act on nasal mucosa to produce characteristic symptoms

Nursing Implications for H1

ASSESSMENT: determine reason for giving medications and assess accordingly; assess airway in anaphylactic client if elderly patient, monitor carefully for safety and start fall risk measures, assess for resolution of rash if applicable. ADMINISTRATION: iF given for prevention of reaction give 30 minutes prior to event, PO should be given with food if possible and it is okay to open capsule and sprinkle on food to administer, IV push over 1 to 2 minutes; give deeply into a large muscle mass to decrease tissue irritation he or she injects IV slowly over a few minutes because severe hypotension may result from rapid IV injection, check y-site for compatibility

Drugs that increase effects of H1 Receptors

Alcohol and other CNS depressants, MOA inhibitors (decreases metabolism increases the duration of action and increase sedative effects), phenothiazines (increase risk of arrhythmia and excessive drowsiness) pramlintide (increase constipation) Tricyclic antidepressants (increase antichologeric side effects)

Hypersensitivity

Allergic reactions that are exaggerated responses by the immune system produce tissue injury and may cause serious disease, may result from specific antibodies, sensitized T-lymphocytes, or both

Anaphylactoid Reactions

Anaphylaxis like reaction to a substance without development of IgE antibody that may occur on first exposure to the causative agent

Allergic Drug Reactions

Any drug, any tissue any part of the drug, 7 to 10 days after initial exposure,

Other Drugs in H1 Receptor Class

Bromphenramine (minimal drowsiness and some antidepressant effects), Chlorpheniramine (Negligible drowsiness usually combines with Hydrocodone as Tussionex for treatment of cough and upper respiratory symptoms associated for adults and children 6 years and old), Dechlorphreniramine (used to treat runny nose, watery eyes, hives, itching), Hydroxyzine (Promethazine, injection for nausea and vomiting or to provide sedation Black Box warning severe chemical irritation and damage to tissues regardless of the the route of administration, don't give it children younger then 2 years old, also reported cholestatic jaundice(

General Characteristics of Second Generation H1 Receptor Antagonists

Do not readily enter the brain from the blood, fexofenadine (allegra) and other drugs in the this class bind preferentially to peripheral rather than central H1 receptors which decreases side effects as results, supplanting the first generation H1 receptor antagonists in the symptomatic treatment of allergic rhinitis and in the relief of pruirtus in urticaria, have a mild beneficial effect in chronic asthma, Fexofenadine (Allegra) is the prototype, last longer then first generation H1. Standard dose 10 mg once daily

Safety Alert for Diphenhydramine

Don't take within 14 days of taking MOA because the risk of overstimulation of sympathetic nervous system

AntiCholinergic

Drowsiness, urinary retention, tachycardia, hypertension, vertigo, dry mouth, increased appetitite

Antihistamine

Drugs that antagonize the action of histamine commonly the H1 receptor antagonists, found in the CNS, discharged from mast cells and basophils in response to particular stimuli, binds with histamine receptors on target organs

Histamine

First chemical mediator releases in immune and inflammatory response found mainly in mast cells surrounding blood vessels, synthesized and stored in most body tissues, concentrated in environmentally exposed tissue such as the eyes, nose, GI tract and lungs

Antigen

Foreign molecule that when introduced into the body triggers the production of antibody by the immune system

Histamine 2

Found in the stomach, stirs stomach acid and pepsin, decrease immunological and proinflammatory reactions

Effects of Histamine Binding with H1 and H2 Receptors

Happens on target organs, contraction for smooth muscle in bronchi and bronchioles, reflex bronchoconstrction and cough, permeability of veins and capillaries which allows fluid to flow into subcutaneous tissues and form edema, increases secretion of mucous glands (nasal congestion); stimulation of sensory peripheral nerve endings to cause pain pruritus (especially prominent with allergic skin disorders)

5 types of antibodies

IgE, IgG, IgM, IgA, IgD; all are produced by B lymphocytes ; found in the blood and are used by the immune system to identify and neutralize foreign objects; allergic reactions are essential antibody reactions

Type III

IgG or Igm mediated reaction characterized by formation of antigen-antibody complexes that induce an acute inflammatory reaction in the tissues, serum sickness is the prototype of these reactions, occurs , may cause permanent tissue damage most common is penicillin allergy or snake venom antiserum

Allergic Food Reactions

Immune response to ingestion of a protein, shellfish, fish corn, seeds, bananas, egg, milk, soy, peanut, tee nuts, higher risk of triggering anaphylaxis, children allergic to milk eggs wheat soy, may outgrow t heir allergy no known preventative

Type IV - Delayed Hypersensitivity

Lag time from exposure to antigen until response is evident, a cell mediated response in which sensitized t lymphocytes react with an antigen to cause inflammation mediated by release lymphokines, direct cytotoxicity or both example is the tuberculin test , contact dermatitis, graft rejection

Second Generation H2 Other Drugs in Class

Loratadine (Claritan, take on empty stomach), Cetrizine (Zyrtec) Desloratadine (Clarinex) Azelastine (Astelin, nasal spray for topical use, can be OTC), Levocetrizine (Xyzal) Olopatadine (Patanol . used as a nasal spray for topical use, less sedation but should not perform activities that require alertness until they are sure they can engage activities safely only available by script)

Patient Teaching H2 Receptors

May cause drowsiness, although much less likely to occur than with other antihistamines because does not cross the blood brain barrier, take med as directed, safer for older adults, be careful dosing those with renal impairment

Patient Teaching H1 Receptors

May cause drowsiness, should not drive or operate machinery, may cause dry mouth use mouth rinses and increase fluid intake if not avoid alcohol, to prevent motion sickness take 30 to 60 minutes

Type II

Mediated by IgG or IgM generating direct damage to the cell surface, include blood transfusion, hemolytic disease of newborns, autoimmune hemolytic anemia and some drug reactions, thrombocytopenia (adverse reaction to penicillin)

Symptoms of Allergic Rhinitis

Nasal congestion, itching, sneezing, watery drainage, itching or throat, eyes and ears are common

Allergic Reaction

Occurs when the immune system overacts to harmless substances known as allergens, substances such as pollen, nuts, dust mites, pet dander, and insect bites, antibodies travel to cells release chemicals causing symptoms most often lungs, nose, sinuses, skin or throat

Type I - Immediate Hypersensitivity

Occurs within minutes of exposure to antigen, IgE induced response triggered by interaction of antigen with antigen specific IgE bound on mast cells causing mast cell activation, histamine and other mediators are released immediately and cytokines chemokines and leukotriens are synthesized after activation, anphylaxis is a type. Can be mild or severe, 10% are severe with shock and cardiovascular collapse due to dilation, pooling of blood, severe hypotension, functional hypovolemia and respiratory distress-fatal.

Histamine 3

Primarily found in the brain ; play a part in regulating Histamine and other neurotransmitters from neurons

Antihistamine Indications

Relieve symptoms but do not relieve hypersensitivity, used for allergic rhinitis, anaphylaxis, allergic conjunctivitis, drug allergies, pseudo-allergies, blood to blood product transfusions, dermatological conditions

Seasonal (Hay Fever) Rhinitis

Response to airborne pollens from trees, grasses and weed mainly in spring and falll

Perennial Rhinitis

Response to non-season allergens such as dust mites, molds, animal dander

Fexofenadine (Allegra) is the prototype

Route/Dosage - PO 60 mg BID, PO 180 once a day,

Two Types of Allergic Rhinitis

Seasonal and Perennial

Anaphylactic Reaction

Severe whole body reaction after sensitization to an allergen causing severe allergic response

Safety Alert for Fexofenadine

Take tablets on an empty stomach after placement on the tongue the tables dissolve in minutes and swallowing with our without water may occur

Serum Sickness

Type III hypersensitivity response is an IgG or IgM mediated reaction characterized by formation of antigen antibody complexes that induce an acute inflammatory reaction in the tissues

Allergic Dermatitis

Type IV reaction, direct contact with an antigen, affected areas are usually on the skin inflamed warm tend to touch, pruritic, edamatous, skin lesions

Diphenhydramine

Well absorbed after oral administration, immediate release oral forms act within 15 to 60 minutes and last 4 to 6 hours metabolism in liver excretes in liver with 24 hours, used for allergic rhinitis, conjunctivitis, dermatitis motion sickness insomnia and Parkinson, PO OR IV, IM- 25-50 MG EVERY 4-6 HOURS, TOPICAL- APPLY TO AFFECTED AREAS 3-4 TIMES A DAY, DRUG-DRUG: INCREASED RISK OF CNS DEPRESSION WITH OTHER ANTIHISTAMINES, ETOH, OPIOID ANALGESICS

Drugs that Interact Fexofenadine

alcohol, cannabinoids, oxycodone (increase sedation) Azole Antifungals (Increase plasma concentration) Antacids containing magnesium or aluminum (decrease the absorption) Rifampin ( decrease metabolism) , fruit juice St Johns Wort High Fat meals

First Generation H1 Receptor Adverse Reactions

drowsiness, anticholinergic, can cause excitement in children, use small doses in children, older patients have a concern for syncope dizziness falls sedation men prostatic hypertrophy can't urinate

Histamine 1

located mainly on smooth muscle cells in blood vessels and respiratory and GI tracts, related allergic response, chemically released when there an immune or inflammatory response, discharged from mast cells and basophils in response to certain stimuli

General Characteristics of First Generation H1 Receptor Antagonists

prevents and reduces most physiologic effects that histamine produces at receptor sites, inhibits smooth muscle constriction in blood vessels, respiratory, GI tract, decrease capillary permeability, decrease salivation and tear formation. Diphenhydramine (Benadryl) is a prototype, contraindications are hypersensitivity, acute asthma attacks, elderly should not recieve diphendramine if avoided if administered should be a decreased dose