Adverse Drug Reactions (ADR)
Content
• Side effects and toxic effects
• Classification of Adverse Drug Reactions
• Hypersensitivity reactions
• Factors modifying drug effects
Intended Learning Outcomes
At the end of this
lecture, student will be able to
• Differentiate between side effects and toxic effects
• Classify Adverse Drug Reactions
• Describe hypersensitivity reactions
• Explain the factors modifying drug effects
Adverse
Drug Reactions
• Any response to a drug i.e. Noxious, unintended
• Occurs at doses used for prophylaxis, diagnosis, therapy
• Excludes drug overdose, abuse, therapeutic errors
• Drug tolerance – close to ADR
Administration
of drugs may result into:
• Side effects: dryness of mouth with atropine
• Untoward effects
– Resistant staphylococcal diarrhea with tetracycline
therapy
• Toxic effects:
– Respiratory depression with morphine
• Allergic/ idiosyncratic reactions
– Salicylates – hemolysis (G6PD deficiency)
ADR Types
Type A
•Augmented
Type B
•Bizarre
Type C
•Chronic
Type D
•Delayed
Type E
•End of dose
Immunity
1. Innate immune system
• Mast cells, epithelial cells, NK cells, Macrophages,
Dendritic cells, N, B, E
• Destroy withoput prior exposure
2. Adaptive immune system
• Cell mediated immunity ( T cells)
• Humoral immunity (B lymphocytes)
Hypersensitivity
• Type I (Immediate
hypersensitivity)
– Ag + Reaginic Ab – degranulation of mast cells &
basophils
– Anaphylaxis
• Type II (Cytotoxic
reaction)
– Ag + Ab – destruction by lysis or phagocytosis
– Chloramphenicol – Autoimmune hemolysis
• Type III (Immune
complex mediated)
– Ag + Ab – form immune complexes
– Serum sickness
• Type IV (Cell
mediated/ delayed hypersensitivity)
– Ag contact T lymphocyte
– Contact dermatitis by chemicals, dust, chlamydia
Manifestations
of ADR
• GIT
• Hemopoietic
• Hepatocellular
• Cardiac
• Renal
• Taste and smell
• Ocular
• Ototoxicty
• Dermal
• Electroloyte disturbances
• Endocrine disturbances
• Behavioral and CNS
• Carcinogenesis
• Teratogenicity
• Exacerbation of disease
• Iatrogenic disease
• Immunosupression
• ADR – abrupt withdrawl
Factors
Modifying Drug Effects
• Body weight
• Age
• Pregnancy and lactation
• Diet, tobacco, alcohol & environment
• Route of administration
• Psychological factors
• Genetic factors
• Metabolic disturbances
• Presence of disease
• Cumulation
• Other drugs and chemicals
• Synergism / Antagonism
• Drug tolerance
• Drug dependence
Summary
• Administration of drug may result into side effects,
untoward effects, toxic effects, allergic/ idiosyncratic reactions
• ADR types:
– Augmented
– Bizarre
– Chronic
– Delayed
– End of dose
• Various factors modify drug effects: Metabolic
disturbances, Presence of disease, Cumulation, Other drugs and chemicals
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