Adverse Drug Reactions (ADR) Introduction.pptx

Adverse Drug Reactions (ADR) Introduction.pptx

1. Adverse Drug Reactions (ADR) By Salaj Khare

2. Overview Definition of ADRs Importance of ADRs Classification of ADRs Factors affecting ADRs

3. Adverse Drug Reactions (ADRs) ADRs are harmful & undesirable effect of drug occurs during clinical use. WHO definition: “Any noxious & unintended response of a drug, that occurs at doses normally used in man for prophylaxis, diagnosis or therapy of disease”

4. Adverse Drug Reactions (ADRs) When occurs… May require treatment or decrease in dose or caution in the future use of the drug. Serious ADRs may be results in temporary or permanent damage, disability or death.

5. Why are ADRs important ? ADRs are major clinical problem Increases morbidity and mortality rate ADRs are 4 th leading cause of death Increases rate of hospitalization Increases cost of therapy Causes failure of the therapy

6. Classification of ADRs Depending on Onset of event: Acute (with in 60 minutes) Sub-acute (1 to 24 hrs) Latent (> 2 days)

7. Classification of ADRs Depending on Severity: Minor : No treatment, antidote or prolongation of hospitalization is required. Moderate : Requires specific treatment, change in drug therapy or prolongs hospital stay. Severe : Potentially life-threatening, causes permanent damage or requires intensive medical treatment. Lethal: Directly or indirectly contributes to death of the patient.

8. Classification of ADRs Based on types of reaction : Type A (Augmented ) Most common type of ADRs . Dose related and predicted due to known pharmacology of the drug . Required- Dose reduction or withdrawal. Ex- Beta blockers – Bradycardia Anticoagulants - Bleeding

9. Classification of ADRs Type B (Bizarre) Unpredictable and non dose related Have no direct relationship to the dose of the drug or the pharmacological mechanism of drug action. Develop on the basis of: Allergy reactions or Idiosyncratic reactions Required- immediate withdrawal of the drug and avoid in future. Ex- Immunologic reactions: penicillin-- anaphylaxis Idiosyncratic reactions: General anesthetics-- malignant hyperthermia

10. Classification of ADRs Type C ( Chronic) Uncommon type, dose and time related They are mostly associated with cumulative-long term exposure of drug Required- Reduce dose or use an alternate therapy and prolonged withdrawal Ex- Paracetamol -- Hepatotoxicity Corticosteroids-- Hypothalamic-pituitary suppression

11. Classification of ADRs Type D (Delayed) Mostly rare, usually dose related. Occurs after many years of treatment Can be due to accumulation Ex- Teratogenesis (Phocomelia)-- Thalidomide Secondary tumours -- Chemotherapy

12. Classification of ADRs Type E (End of Use) Rare or unpredictable Occurs soon after withdrawal of the drug or stopped abruptly Required- Reintroduce drug and withdraw slowly Ex- Phenytoin withdrawal-- Seizures Withdrawal syndrome with opiates or benzodiazepines (e.g., insomnia, anxiety)

13. Classification of ADRs Based on predictability: Type A and Type B Type A - are dose related and predictable, based on pharmacological properties. Type A effects are due to - Overdose or toxic effects- excessive p’cological effects due to high dose or prolong use Ex- Barbiturates- Coma Side effects- Unwanted but often unavoidable effects of drug that occur at therapeutic doses Ex- Atropine- dryness of mouth

14. Classification of ADRs Secondary effects- Indirect consequences of a primary action of the drug Ex- Tetracyclines suppress GI bacterial flora- Superinfections Drug interactions- P’cological activity of one drug altered by another drug or other substance Ex- Toxicity of theophylline in presence of erythromycin therapy

15. Classification of ADRs Type B - are not dose related and unpredictable, not related to pharmacological properties of drug. Type B effects may happen due to – Intolerance- Appearance of characteristic toxic effects of a drug in an individual at therapeutic dose Ex- Chloroquine (single dose) – causes vomiting and abdominal pain Idiosyncratic reactions- Genetically determine abnormal reactivity of drug Ex- Chloramphenicaol – aplastic anemia in rare individuals

16. Classification of ADRs Hypersensitivity reactions (immunological)- Immunological mediated reactions Ex- Methyldopa- hemolytic anamia Pseudo-allergic reactions- produce same symptoms with allergic reactions but are not immunological mediated Ex- NSAIDs- causes angioedema and anaphylaxis

17. Factors affecting ADRs Age of the patient Patho -physiological conditions (multiple disease) Amount of drug administered- overdosing or prolonged therapy Pregnancy Previous history of allergy Racial or genetic differences Multiple drug therapy Drug Abusers and addicts

18. Thank You