Adverse Drug Reactions and Drug Allergy Adverse Drug Reactions and Drug Allergy
1. ADVERSE DRUG REACTIONS (ADRs) AND DRUG ALLERGY Achara Srisodsai, Ph.D. Department of Toxicology Faculty of Pharmaceutical Sciences Khon Kaen University
9. Compound Success Rates By Stages 0 2 4 6 8 10 12 14 16 Years Discovery (2-10 Years) Preclinical Testing Laboratory and animal testing Phase I 20-80 healthy volunteers used to determine safety and dosage Phase II 100-300 patient volunteers to look for efficacy and side effects Phase III 1,000-5,000 patient volunteers used to monitor adverse reactions to long-term use FDA Review/Approval Additional post-marketing testing Compound Success Rates by Stage 5,000-10,000 screened 250 Enter preclinical testing 5 Enter clinical testing 1 Approved by the FDA Postmarketing survillence
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11. Adverse Reaction Drug Time Lag (yr) Pulmonary embolism Oral contraceptives 3 Myocardial infarction Oral contraceptives 5 Deaths from asthma Sympathomimetic aerosols 4 Jaundice Halothane 7 Colitis Lincomycin 6 Colitis Clindamycin 5 Aplastic anemia Phenylbutazone 6 Venning, GR. Br. Med. J. 286:365-368, 1983 Summary of time lags after U.S. marketing before adverse drug reactions were widely recognized
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13. Required sample size for detecting a rare adverse drug reaction Number of patients to be observed to detect Incidence of ADR 1, 2 or 3 cases of ADR 1 2 3 1 in 100 300 480 650 1 in 200 600 960 1,300 1 in 1,000 3,000 4,800 6,500 1 in 2,000 6,000 9,600 13,000 1 in 10,000 30,000 48,000 65,000
15. WHO: Any response to a drug which is noxious and unintended , and which occurs at doses normally used in man for prophylaxis , diagnosis , or therapy of disease, or for the modification of physiological functions. What is ADR?
24. 3. Type C (chronic) - เกิดขึ้นภายหลังจากการใช้ยาติดต่อกันเป็นระยะเวลายาวนาน แต่สามารถคาดการณ์ล่วงหน้าได้ เช่น อาการติดยากลุ่ม Benzodiazepines 4. Type D (delayed) - เป็นการเกิดอันตรายจากการใช้ยาแบบมีระยะแฝงนาน เช่น การก่อมะเร็ง หรือ การก่อความพิการต่อทารกในครรภ์ 5. Type E (end-of-treatment) - อาการเกิดภายหลังการหยุดใช้ยา (withdrawal) อย่างกะทันหัน
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26. Causes of Type A reactions 1. Pharmaceutical causes - Drug quantity - Drug release e.g. Osmosin ® (slow release indomethacin) GI bleeding 2. Pharmacokinetic causes - Drug absorption - Drug elimination - Drug distribution - Drug metabolism 3. Pharmacodynamic causes - Drug receptors - Homeostatic mechanisms - Disease
30. Factors predisposing to pharmacological adverse drug reactions Factor Example Toxicity Mechanism Pharmaceutical Osmosin Gastrointestinal Release of high (slow release bleeding concentrations of indomethacin) active drug locally in GI Pharmacokinetic* Digoxin Digoxin toxicity Decreased elimination (nausea, arrhythmias) if renal function is impaired Pharmacodynamic Indomethacin Left ventricular Water and sodium failure retention Drug-drug Terfenadine TM Prolonged QT Inhibition of interaction* Erythromycin interval and metabolism of torsades de terfenadine by pointes erythromycin *Can affect absorption, distribution, metabolism, or excretion.
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38. ตารางเปรียบเทียบ Type A และ Type B ADRs Type A Type B 1. Predictability 2. Dose-dependent 3. Incident 4. Mortality 5. Treatment 6. Pharmacological basis 7. Seriousness Yes No Yes No Common Rare No Yes Adjust dose No Yes No No Yes
45. Type I — Anaphylactic/ Immediate type (e.g., Penicillin, insulin urticaria or anaphylaxis) Type II — Cytotoxic type (e.g., drug-induced haemolytic anaemia or thrombocytopenia [reduced platelets]) Type III — Immune complex type (e.g., serum sickness-like drug reactions) Type IV — Cell-mediated or delayed hypersensitivity (e.g., neomycin contact dermatitis) กลไกของการแพ้ยา