BDS 1st year theory class

1. Adverse Drug Reactions
Dr. Pravin Prasad
MBBS, MD Clinical Pharmacology
Assistant Professor
Maharajgunj Medical Campus, TU
3 March 2020 (21 Falgun 2076), Wednesday
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2. By the end of this discussion, BDS 1st year
students will be able to
Define and Understand different
terminologies related to adverse drug
reactions (ADRs)
Classify types of ADRs
Give examples of different types of ADRs
Briefly outline causality assessment of ADRs
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3. Adverse Drug Effects: Terminologies
Adverse Drug Event:
Any untoward medical occurrence that
may present during treatment with the
medicine, but which does not necessarily
have a causal relationship with the
treatment
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4. Adverse Drug Effects: Terminologies
Adverse Drug Reaction(ADR):
An appreciably harmful or unpleasant
reaction, resulting from an intervention related
to the use of a medicinal product, which
predicts hazard from future administration
and warrants prevention or specific treatment,
or alteration of the dosage regimen, or
withdrawal of the product.
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5. Picturising the concepts
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Adverse events
Adverse drug events
No causal relationship
Adverse drug reactions
Causal relationship
present

6. Adverse Drug Effects: Terminologies
Side Effects:
Minor effects of type A events/effects
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7. Adverse Effects: Classification
Type Mechanism Examples
A
Augmented,
dose related,
Predictable
• Postural hypotension
with anti-hypertensives
• Hypoglycaemia with
hypoglycaemics
• Hypokalemia with
diuretics
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8. Adverse Effects: Classification
Type Mechanism Examples
B
Bizzare,
idiosyncratic,
not dose
related, Non-
predictable
• Antibiotic induced rash
• Phenytoin induced
Steven-Johnson
Syndrome/ Toxic
Epidermal Necrolysis
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9. Adverse Effects: Classification
Type Mechanism Examples
C
Chronic/contin
uous, time
related
• Analgesic Nephropathy
• Dyskinesia with
Levodopa
D Delayed
• Thalidomide induced
phocomelia
• Vaginal cancer due to
diethylstilbestrol
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10. Adverse Effects: Classification
Type Mechanism Examples
E
End of
treatment
• Adrenocortical insufficiency
due to abrupt corticosteroid
withdrawal
• Opioid withdrawal causing
withdrawal syndrome
• Insomnia due to abrupt
benzodiazepam withdrawal
Others: Type F, Type G
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11. Adverse Effects: Classification
According to severity, as:
Mild
No therapy, antidote or prolongation of
hospitalization is required
Moderate
Requires change in drug therapy, specific
treatment or prolongs hospital stay by at
least one day
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12. Adverse Effects: Classification
According to severity, as:
Severe
Potentially life threatening, causes permanent
damage or requires intensive medical
treatment
Lethal
Directly or indirectly contributes to death of
the patient
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13. ADRs: WHO Classification
Temporal
relationship
Previous
Knowledge
De-challenge Re-challenge
Explained by disease or
other drugs
Definite 
(plausible)
 
(plausible)
 
(Cannot be explained)
Probable 
(reasonable)
 
(clinically
reasonable)
 
(Unlikely)
Possible 
(reasonable)
 
(lacking or
unclear)
  / 
(Could be)
Unlikely  / 
(improbable)
 
(plausible)
Conditional/
Unclassified
More data for proper assessment needed; additional data under
examination

Unassessable or
unclassifiable
Report suggestiong and adverse reaction; cannot be judged: information insufficient or
contradictory; data cannot be supplemented or verified
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14. ADRs: Other Classification
Classification Comments
Schumock and Thornton
Preventability criteria
Preventibility of ADRs
Naranjo Algorithm Casuality Assessment
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15. Naranjo Algorithm
Yes No Do not
Know or
Not Done
Are there previous conclusive reports on this reaction? +1 0 0
Did the adverse events appear after the suspected drug was given? +2 -1 0
Did the adverse reaction improve when the drug was discontinued or a specific
was given?
+1 0 0
Did the adverse reaction appear when the drug was re-administered? +2 -1 0
Are there alternative causes that could have caused the reaction? -1 +2 0
Did the reaction reappear when a placebo was given? -1 +1 0
Was the drug detected in any body fluid in toxic concentrations? +1 0 0
Was the reaction more severe when the dose was increased, or less severe when the
was decreased?
+1 0 0
Did the patient have a similar reaction to the same or similar drugs in any previous
exposure?
+1 0 0
Was the adverse event confirmed by any objective evidence? +1 0 0
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16. Naranjo Algorithm: Interpretation
Calculated Score Intrepetation
≥ 9
Definite Adverse Drug Reaction
(ADR)
5-8 Probable ADR
1-4 Possible ADR
0 Doubtful ADR
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17. Preventability criteria according to
Schumock and Thornton scale
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18. Any queries?
Thank you…
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