El Delta Hypersensitivity Reactions PDF 2025

 introduction  The modern dentist uses a wide variety of drugs to treat patients, including antibiotics, hypnotics, and anesthetics.  All practitioners who use these medications must know how to manage adverse reactions triggered by these agents.  A dental practitioner also uses a wide ran...

 introduction  The modern dentist uses a wide variety of drugs to treat patients, including antibiotics, hypnotics, and anesthetics.  All practitioners who use these medications must know how to manage adverse reactions triggered by these agents.  A dental practitioner also uses a wide range of materials such as impression materials, adhesives, latex, and restorative and endodontic materials that contain potential allergens. These include preservatives, coloring agents, fixatives, binding agents, flavorings, and latex.  An altered reactivity of the tissues of certain individual,  Overactive immune response ▪ Reaction out of proportion ▪ Reaction against harmless matters  According to the basic immune reaction involved in their production: Type I Anaphylaxis (Generalized & Localized) Type II Cytotoxic.(antibodies mediated) Type III Immune complex. Type IV Cell mediated. Types I, II, III: Immediate allergic reactions Type IV: Delayed allergic reaction.  Type I ( anaphylaxis)  Acute allergic reactions  Mediated by IgE  The most serious of allergies.  Require immediate recognition and management.  Type I ( anaphylaxis) Generalized anaphylaxis Localized anaphylaxis It is a term used when several It is a term used when a organs and tissues are affected reactions involve one organ or one system. Example: Anaphylactic shock. Example: 1. Bronchial asthma (respiratory system is the target). 2. Urticaria (the skin is the target) 3. Angioedema 4. Hay fever  It is an antigen (foreign substance) that can elicit allergic reaction. (i.e can elicit (IgE) production (in some individuals).  Allergic response to allergen may occur secondary to: a) Inhalation b) Injection c) Ingestion d) Contact with skin Routes of administration of allergen Allergen Sensitizing dose:- Is responsible for the first exposure of the individual to the antigen (i.e leads only to IgE production). Challenging dose:- Corresponds to the exposure to the same antigen or chemically related antigen (Cross allergy).  The patient is initially exposed to the antigen  lead to formation of specific Ig E by plasma cells Ig E circulates in the blood stream and binds to mast cells mast cells  On re-exposure to the same antigen or become sensitized. chemically related antigens results in binding of the antigen to the IgE on the sensitized cells  A latent period of variable duration (several hours, several days to possibly years) during which Ig E continues to be produced and attached to basophils, eosinophils & mast cells.  After this latent period  high levels of Ig E plus sensitized basophils & mast cells are present. It is the reaction of antibody with an antigen other than the one which induced its formation.  IgE interacts only with a particular antigen or with a chemically related antigen Example: Allergy to chemically related drugs, Patient allergic to one drug is also allergic to the chemically related drugs, e.g.; 1. Procaine and sulpha 2. Penicillin and cephalosporine. Q-  After production of IgE,  It binds to high affinity receptors for IgE on mast cells, basophils & eosinophils.  IgE cross link the cells to a particular allergen  degranulation of the cells  release of the Histamine and other vasoactive supstances 1. Possession of high affinity receptors for IgE (there are 105 106 receptor sites per cell). 2. Histamine containing granules (which constitute 10% of the cell’s weight) A. Preformed granules B. Synthetized substances upon activation from mast cell wall. (synthetized de novo).  Preformed intracellular Synthetized substances from the granules cell wall (synthetized de novo) Immediate reaction  Arises within seconds to ½ an Late phase reaction hour  Takes up to 8-12 hours to  The more rapid clinical develop. feature, more severe reaction.  Less dramatic. Mediators include 1. Histamine 1. leukotreins 2. Proteoglycans 2. Prostaglandins 3. Platelet activating factor (PAF) Slowly Reacting Substances 4. Eosinophil chemotactic factor (ECF) (SRS) of anaphylaxis 5. Neutrophil chemotactic factor (NCF)  a group of allergic diseases of hereditary tendency, e.g. bronchial asthma and hay fever.  The production of IgE enhanced by host genetic factors  Atopic individuals have higher level of IgE & eosinophils Definition: It is the that may follow administration of a to which the subject has become Notice that; anaphylactic = without protection (ana = without) prophylactic = with protection. (pro=with)  The reaction usually starts within 30 minutes (may be 30 seconds) after injection of a drug. The quicker the onset, the more severe the reaction. The reaction may take more than ½ an hours to start after oral administration of the drug (due to the slower absorption) ………………… (Q- Give a reason). It starts with: Paresthesia of the face. Coldness of hands & feet. The face become edematous. Pulmonary symptoms: start to wheeze due to bronchospasm. G.I.T. manifestation as; vomiting, cramps & diarrhea. Facial edema Skin hives 1. Rapid fall of blood pressure. 2. Pallor and sweating. 3. The pulse is rapid and weak. 4. Loss of consciousness. 1. Pulse less. 2. Cyanotic from inadequate oxygenation of the blood. 3. Death may occur within few minutes.  During the life-threatening phase (Stage-I) of anaphylactic shock, the following 3 steps should be done: 1. Position: Lay the patient flat with legs raised (supine position), to improve venous return from the peripheral regions to the heart and increases blood flow to the brain. 2. Adrenaline 3. Oxygen supply & monitoring of vital signs until an improvement in patient status (Blood pressure and pulse rate).   Adrenaline for adult I.M 0.5 ml of 1:1000 of epinephrine solution Re-administrated after 5 min if no improvement with maximum dose 1.5 ml in 15 min , smaller doses from 0.1 to 0.3 mL should be used for children, depending on their size.  oxygen and monitoring of vital until an improvement in patient status NOTICE: 3 steps must be followed during the life- threatening phase of anaphylactic shock 1) Position 2) Adrenaline 3) Oxygen The site for I.M. injection of adrenaline: Traditional I.M. site (mid- deltoid) Stage-II: to prevent recurrence of symptoms and to decrease the need for continuous administration of adrenaline, do the following steps: 4. Call ambulance. 5. Hydrocortisone sodium succinate 200 mg I.M or I.V. 6. Anti-histaminics. Notice that: - Drugs in step (5 & 6) are not administered during the acute phase. - They may be given on arrival in the office while or after transporting the victim to the hospital emergency department for definitive care. -.  Hydrocortisone sodium succinate 200 mg I.V every 6 hour for 24 hours  Antihistaminic 50 mg of diphenhydramine I.M. Action: 1. Bronchodilator. 2. Vasoconstrictor 3. Decrease capillary permeability, thus reduce edema. 4. It acts within few minutes leading to increase in blood pressure and stimulation of heart muscle. (so, it is considered life saving in anaphylactic shock). Dose: 0.5 ml of 1/1000 conc. S.C. or I.M; the maximum dose 1.5 ml (3 injections over a period 10 – 15 minutes), - For children 0.1 – 0.3 ml, & for infant=0.075 ml. Injection Site: Intra-lingual or floor of mouth, even in the presence of hypotension, will provide rapid absorption than is seen in the traditional site (mid-deltoid). N.B; Never injected I.V. to avoid Ventricular fibrillation. (Give a reason, Question????) Action: 1. Used to prevent recurrence of symptoms. 2. Anti-inflammatory and immunosuppressive Dose: 200 mg I.V. They are of no value in emergency treatment (Why?): They are slowly acting drugs. They antagonize one mediator only (histamine) They restore the vasomotor tone without producing potential vasoconstriction. Example: Promethazine HCI: 20-50 mg oral or I.M. every 24 hours. Long acting 20-24 hours. Highly sedative 8-12 hours, So, it is best taken at night. Antihistaminics Patients who have had an anaphylactic attack should carry self-injectable epinephrine. Is it possible to prevent the drug allergy? It is impossible to prevent drug allergy, but rather to minimize the risk (How?).  Careful Case History A- Previous drugs (allergen) reaction: Taking into consideration the nature of the allergens and cross reactivity. B- History of atopic allergic diseases (Hay fever, asthma) or any allergic reactions. C- The patient must be informed about his hypersensitivity to any drugs e.g.; LA.  Drugs which can be taken I.M. or S.C. should not be taken I.V.  Keep the patient under observation for 30 minutes after injection of a drug (Why?). Serious reaction occurs within the 1st 30 minutes after I.V. drug administration.  Dentists must be ready and equipped by: A. Good medical information. B. Suitable medications. C. Good equipment: e.g.; preloaded syringe of adrenaline for emergency.  Patients must be advised to test their allergy to any drug when indicated. The Skin test for allergy in atopy Aim: to detect Ig E circulating antibodies. Steps:  The skin is marked for testing a group of appropriate allergens for the patient.  A drop of allergen solution is placed into the skin at each mark, using a fresh fine sterile needle or lancet is used to gently introduce a minute volume of allergen solution into the dermis.  After 10-15 minutes the results are interpreted. The Positive reaction Interpretation of the results The presence of a raised wheal at the site of the allergen skin prick test of 3 mm or greater in diameter, indicates the presence of IgE antibodies specific to that allergen. Negative response means that the patient can safely receive the tested drug. Skin test may give false-positive results  produced by the localized release of histamine in response to skin puncture by the needle. We can’t use the skin of allergic patient for doing the test (e.g.; local anesthesia) in dental office …… (Why?)  Because even a minute amount of L.A. being employed (0.1 ml) might precipitate an immediate anaphylaxis in the susceptible patient.  One Organ is Involved 1. Urticaria 2. Hay fever 3. Angioedema 4. Bronchial asthm It is a common allergic reaction of the skin. 1. It varies from small localized papules to large coalescing erythematous plaque. 2. Severe itching. Avoidance of the causative factor, as much as possible. Anti-histaminics. Corticosteroids in severe cases. It is a recurrent form of allergy to wind-born pollen grains of grasses and trees, certain food or dust. There appears to be familial predisposition to allergy and has a seasonal incidence particularly in early summer. Itching of the nose with profuse watery nasal discharge (Runny nose). Paroxysms of sneezing & coughing. Conjunctival irritation & lacrimation. Headache & depression. Avoid contact with the causative pollen (travel to the sea - shore). Anti-histaminics. Steroids in cases refractory to anti-histaminic. Love oral medicine.. Love MAX