This document discusses adverse drug reactions (ADRs), defining them as unintended and harmful responses to drugs taken at normal doses for treatment or diagnosis. ADRs can be classified in several ways, including by cause (type A to E reactions) and effect (toxic, allergic, withdrawal, etc.). Common type A reactions are dose-dependent and predictable, while type B reactions are unpredictable and not dose-related. The document also covers idiosyncratic reactions, drug dependence, carcinogenicity, pharmacovigilance and more.

1. ADVERSE DRUG REACTION
(ADR)
LECTURER-
MANI GOEL

2. WHO defines an ADR as “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 function”
Three important points:-
Noxious / harmful response
Normal doses
For treatment prophylaxis
and diagnosis
INTRODUCTION

3. Adverse Drug Events
Medication
Errors
(preventable)
Adverse Drug
Events
(ME & ADR)
Adverse drug event:-
“Any untoward medical occurrence that may present during
treatment with a medicine, but which does not necessarily
have a causal relationship with the treatment”

4. According to cause
Type A (Augmented)
Type B (Bizarre)
Type C (Chronic)
Type D (Delayed)
Type E (Ending of use)
According to effect
Toxic effect
Adverse effect
Local Reactions
Drug Withdrawal Reactions
Drug allergy
Idiosyncrasy
Drug dependency, abuse , addiction
Teratogenicity
DRUG INDUCED
CLASSIFICATION
Adverse effects of drug can be classified in many ways,

5. ACCORDING TO CAUSE
1.Type A (Augmented) :
• Reactions will occur in everyone:
• They are due to excess of normal and hence :
 Predictable,
 dose-related, pharmacodynamic effects.
• Eg; Hypoglycaemia with Insulin,
Bleeding with anticoagulants.
• How to reduce?

6. 2.Type B (Bizarre)
• Reactions will occur only in some people.
• Dose independent and unpredictable
• Eg. Steven johnson to phenytoin
• How to reduce?
 Stop Drug
 Avoid in future
 Instruct to patient

7. STEVENS JOHNSON SYNDROME- TOXIC
EPIDERMAL NECROLYSIS

8. TYPE A
(Augmented Response)
Type B
(Bizarre)
Predictable
Pharmacological
response
Yes No
Dose dependent Yes No
Incidence & morbidity High Low
Mortality Low High
Treatment Change dose Stop

9. 3.Type C (Chronic)
• Reactions due to long-term exposure,
• e.g.
Adrenal axis suppression with steroids
Analgesic nephropathy
• How to reduce?
 Lower dose, short duration.
 Alternate dose

10. 4.Type D (Delayed)
• Effects seen long time after exposure,
• e.g.
Teratogenesis
Carcinogenesis. Seen in children
Adenocarcinoma of Vagina with diethylstilbestrol
- seen in puberty
• How to reduce?
 Use if only highly indicated in pregnancy.

11. 5.Type E (Ending of use)
• Reactions occurs when discontinuation of chronic therapy is
too abrupt, or after withdrawl.
• e.g.
Abrupt discontinuation of opioid causing the withdrawal
syndrome.
Rebound hypertension- in long term use of beta blockers
• How to reduce?
 Taper dose of drug slowly.
 Concomitant dugs used as antagonist.

12. 6.Type F (Failure of Therapy)
• When drug therapy fails to produce desirable effect.
• e.g.
Failure of contraception with OCP’s
• How to reduce?
 Avoid more than two Drugs at same time- Drug Interaction.

13. Intolerance
Idiosyncrasy
Drug allergy
Drug dependency, abuse , addiction
and habituation.
Teratogenicity
Type A (Augmented) Type B (Bizarre)
ACCORDING TO CAUSE
Toxic effect
Adverse effect
Local Reactions
Drug Withdrawal Reactions

14. “There is no drug with single effect”
Safety and tolerability are most significant for the
recipient of drugs.

15. TOXIC EFFECTS
• Effects are dose related and predictable.
• Result of excessive pharmacological action of the drug due to over
dosage or prolonged use (Augmented).
• E.g.
Heparin dec blood clotting- spontaneous bleeding (with overdose)
Insulin dec blood sugar-may cause hypoglycemia (with overdose)

16. • Effects are dose related and predictable.
• Result are different or unrelated to the pharmacological action.
• E.g.
SIDE EFFECTS/ ADVERSE
EFFECTS
A side effect of drug may be beneficial in some extent:
Morphine ( analgesic ) produces constipation ( side effect ), but beneficial in case of
traveler’s diarrhoea.

17. Produced at site of absorption
Eg. Asprin – Gastric Irritation.
Erythromycin – Diarrhoea and cramping.
LOCAL REACTIONS

18. • Non dose related.
• Certain drugs are more allergenic than others.
• Eg. Penicillins- 8% (U.S. population)
Sulfa drugs- 5%
Aspirin- 5%
• Development of an allergic reaction.
ALLERGIC REACTIONS

21. TREATMENT OF DRUG ALLERGY
Stop the offending drug immediately.
In case of anaphylactic shock;
• First, 500 micrograms of adrenaline (epinephrine) injection
(0.5 ml of the 1 in 1000 solution) should be given i.m. to raise
the blood pressure and to dilate the bronchi.
Urticaria
• H1- receptor antihistamine [say chlorpheniramine 10-20 mg by
slow i.v. injection]
• Hydrocortisone (100-300 mg i.m. or i.v.).

22. Implies an inherent qualitative abnormal, unexpected paradoxical reaction to
a drug, usually due to genetic abnormality
• Haemolytic anemia caused by Priamquine in Glucose-6-Phosphate
Dehydrogenase deficiency in RBCs.
• Prolonged apnea caused by pseudo-cholinesterase deficiency.
• With CNS DEPRESSANTS- AMBIEN- produces stimulant effect
CNS STIMULANTS- dexedrine- produces calming effect
IDIOSYNCRACY

23. TERATOGENIC EFFECT
diethylstilbestrol

24. Estrogen
Testosterone
CARCINOGENIC EFFECT

25. IATROGENIC DISEASE

26. DRUG DEPENDENCY
• Drug dependence is a state arising from repeated, periodic or
continuous administration of a drug.
• The subject feels a desire, need or compulsion to continue
using the drug and feels ill if abruptly deprived.
• Drug dependence is characterized by:
Psychological dependence: (for anything)
Craving for anything
Doesn’t effect physical state.
Physical dependence:
Physiological symptoms when withdrawn
Produce opposite effect eg. Narcotic- codeine.

27. PHARMACOVIGILANCE
Pharmacovigilance activities are done to monitor detection,
assessment, understanding and prevention of any obnoxious
adverse reaction to drugs at therapeutic concentration on
animal and human beings
Pharmakon (Greek), “drug;” and Vigilare (Latin), “to keep
awake or alert, to keep watch.”