ADVERSE DRUG REACTIONS

ADVERSE DRUG
REACTIONS

Lecture by Dr.Shehla Shaheen

Adverse effect is a harmful and undesired effect resulting from the administration of a therapeutic dose of a drug. OTHER WORDS USED SYNONYMOUSLY;
SIDE EFFECTS
TOXIC EFFECTS
HARMFUL EFFECTS
UNDESIRABLE EFFECTS

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All drugs can produce harmful as well as beneficial effects.

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ADRs are either related or unrelated to the principal pharmacological actions of the drugs 

Adverse effects are of great concern to drug regulatory authorities.

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Before licensing establishment of safety and efficacy of drugs

TYPES OF ADVERSE DRUG REACTIONS(ADRs):

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Adverse effects related to main pharmacological action of drugs

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Adverse effects unrelated to main pharmacological action of drugs

TYPES OF ADRS

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Type A(Augmented, dose dependant),related to principal pharamcological action.

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Type B(Bizarre, dose independent),unrelated to principal pharamcological action.

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Type C(Continous)reaction

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Type D(Delayed) effects

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TYPE E(Ending of use)reactions.

TYPE A (Augmented dose dependant)

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Adverse effects related to the main pharmacological action of the drug.

These are predictable and action is well understood; eg.
 bleeding with anticoagulants
 Orthostatic hypotension with alpha1adrenoceptor antagonists
 Sedation with anxiolytics.
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Type B(Bizarre, dose independent),
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Adverse effect is unrelated to the principal pharmacological action of the drug. 

May be predictable when a drug is taken in excessive dose .

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occurring with ordinary dose are unpredictable and serious (idiosyncratic reactions) 

Often caused by reactive metabolites or immunologic reactions..

eg.
Paracetamol hepatotoxicity
 Aspirin induced tinnitus.
 Aplastic anemia with chloramphenicol.
Or with a predisposing disorder like
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primaquine induced hemolysis in pts. with glucose-6-phosphatase dehydrogenase deficiency.

Type C(Continous)reaction
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Reactions due to long term use

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Eg.analgesic nephropathy
Tardive dyskinesia