Different types and its mechanism with examples , diagnosis and treatment

1. HYPERSENSITIVITY
REACTIONS OF A DRUG
T.SAI SWAPNA
II/VI PHARM.D
Y17PHD0827
NIRMALA COLLEGE OF
PHARMACY ,ATMAKUR

3. HYPERSENSITIVITY
 Hypersensitivity refers to the undesirable reactions
produced by the normal immune system , including allergies
and autoimmunity
 These reactions may cause damaging , uncomfortable or
occasionally fatal
 These reactions require a presensitized state of the host

4. DRUG HYPERSENSITIVITY;
 It is an immunologically mediated reaction producing
symptoms unrelated to pharmacodynamic actions of the drug
generally occuring with much smaller amounts and have a
different time course of onset and duration
 These reactions account for about 1/6th of all ADR’S
 The most common allergic reactions occurs in skin and
observed 2-3% in hospitalized patients

5.  Antibiotics and antiepileptics are the drugs most frequently
causing hypersensitivity reactions
 The severity and symptoms depends up on the immune
activation and duration of treatment , sex

6. TYPES ;
 1. ANAPHYLAXIS
 2. CYTOTOXIC
 3 . IMMUNE COMPLEX
 4 . DELAYED TYPE

7. TYPES ;
s. no Mechanism Examples
1. IgE mediated hypersensitivity Anaphylaxis , asthma
2. Cytotoxic antibody dependent Haemolytic anaemia
thrombocytopenia
3. Immune complex damage Serum sickness , SLE
4 . Delayed Dermatitis

8. IGE MEDIATED
 IgE antibodies is ready to react to small amounts of antigens
 Stimulate receptors bound ige antibodies
 The drug causes formation of tissue sensitive ige antibodies
that are fixed to mast cells
 Subsequent exposure of drug activate leucocytes and release of
chemical mediators that cause allergy

10. CYTOTOXIC ;
 The mediator of these reactions are IgE /IgM membrane
attack complex
 It results when drug binds to RBC and is recognised by IgE
antibodies
 The Ag- Ab reactions trigger the lysis of RBC either by
activating complement system or by action of cytotoxic T cells
or by phagocytosis of macrophages leads to disintegration of
cell

11. EXAMPLES ;
 Seen in high dose pencillin and cephalosporin
 Quinine induced immune thrombocytopenia
 Heamolytic anemia

12. IMMUNE COMPLEX ;
 These reactions occurs within 1 – 2 hours of drug
administration
 Soluble antigen antibody forms soluble complexes
deposited on vascular endothelium and activate complement
 Characterized by allergic inflammatory reactions in tissues

14. CLINICAL FEATURES ;
 Vasculitis
 Sulphamethoxazole , cephalexin , amoxicillin , NSAID’S
and diuretics

15. DELAYED REACTIONS ;
 These reactions mediated by T cell and macrophages
 Activation of T cell release of cytokines these activate
macrophages and NK cells
 The term delayed because the response occurs after 48 – 72
hours after antigen response
 Pnemonitis , contact dermatitis

16. PSUEDOALLERGY ;
 Pathogenically poorly determined , alternation in
metabolism of histamines .
 Detection of particular immune mechanism is negative
 The exact mechanism is unknown by which these cause
reactions through IgE / T cells or not
 These reactions mainly occurs when taken of NSAID’S

17. CLINICAL SYMPTOMS OF
DRUG HYPERSENSITIVITY;
 Urticaria
 Erythema
 Stevens john syndrome
 Epidermal necrosis

18. DIAGNOSIS ;
 Patient symptomology
 IgE
 Skin testing
 RAST testing
 Antiglobulin test
 ESR , CRP , ANA
 Patch test lymphocyte proliferation assay

19. TREATMENT ;
 Discontinuation of drug
 Alternative medications
 Additional therapy to manage symptoms caused by drugs
 Systemic corticosteroids and antihistamines may improve
dermatological effects

20. THANK YOU