Any undesirable experience
associated with the use of a medical product in a patient.
It is related to prescribing, preparation, dispensing
or administration of medications.[General Definition]
Any response to a drug that is noxious and unintended and that occurs at doses used in humans for prophylaxis, diagnosis or therapy, excluding failure to accomplish the intended purpose [Definition as per Karch & Lasagna]
Any response to a drug that is noxious and unintended and that occurs at doses normally used in humans for prophylaxis, diagnosis or therapy of disease, or for the modification of physiological function. [WHO definition]
Any undesirable experience asssociated with the use of a medical product in a patient. [U.S FDA definition]
Classification of ADRs
Acute
Sub Acute
Latent
Observed within 60 mts after the administration
of a medication
Observed within 1-24 hrs after
the administration of a medication
Requires two
or more days to become apparent.
Eg : Anaphylactic shock, severe
broncho constriction, nauses, vomiting
Hypokalemia
induced by Amphotericin - B (Requires change
in therapy / additional treatment or continued
hospitalization
Hypokalemia
induced by Amphoteicin - B (Requires change
in therapy / additional treatment or continued
hospitalization
Reactions
that are life threatening or those that prolong
hospitalization
Classification III
(Rawlin’s and Thompson’s classification)
Type A (Augmented reactions)
Type
B (Bizzare)
Extend directly from a drug's
pharmacological effects.
They are often predictable and close dependent
Accounts for up to two third of all ADRs.
Includes ADRs resulting from drug overdose
and drug - drug interactions.
The effects are unrelated
to the known pharmacological action of the
drug
They are generally idiosyncratic or immunologic
reactions that are rare.
These reactions are unpredictable and
may or may not be dose dependent
They are particularly dangerous
Their incidence is low but mortality is
high.
Examples :
Examples
:
1. Sedation caused by antihistamines.
Hypotension caused by beta - adrenergic
antagonists.
Aplastic
anemia caused by chloramphenicol.
Rash induced by beta lactam antibiotics.
Anaphylactic reaction to penicillin.
Do Adverse Drug Reactions matter !?!
--- Yes !!!
ADRs matter because pharmaceutical products and other substances taken for medical purposes have the potential for harming patients to the extent of being fatal.
Why do they happen ?
Inevitable reasons
The inevitable reasons are :
The effects of any medical intervention cannot be
predicted with absolute certainty.
There is no drug or medical intervention which will
not have some negative and undesirable effect on someone,
somewhere at some time.
Information about rare events may, by their very nature,
not be available until they happen.
Preventable reasons
The preventable reasons:
An error in diagnosing the disease.
Prescription of the wrong drug for the disease.
Prescription of the wrong dose of the right drug.
Choice of the right drug for the disease, but maybe
the wrong drug for the patient, because of a genetic
or ethnic predisposition, age, some other illness
or medication, allergy or intolerance.
Choice of an appropriate drug but without taking into
account the potentially harmful interactive effects
with other drugs or substances being taken by the
patient.
The full specification, indications, contraindications
and risks of the drug may not have been read or fully
understood.
The patient may not comply with the doctor’s
advice or with the manufacturer’s advice in
the patient information leaflet.
As long as people are choosing drugs and other substances
for their own medication without professional advice,
there may be problems.
The taking of many drugs (polypharmacy) or receiving
treatment form more than one source (polytherapy)
can contribute significantly to causing drug-related
problems, particularly harmful drug interactions.
Causes for ADR
Drugs
Diagnostic Agents
Biologicals
Vaccines
Nutrients
Fluids
Electrolytes
Alternative products
Metabolite of a drug
Pharmaceutical excipient
Component of a drug delivery system
Causes of ADR can be classified as
Pharmaceutical (dosage
form related)
Pharmaceutical (Dosage form
related) Increased drug quantity—Noncompliance with
pharmacopoeial requirements (BP or USP) during drug
manufacture might increase the amount of active agent
in the dosage formulation. Enhanced drug release—Improper
formulation can result in sudden or enhanced release
of irritant agents (eg, potassium chloride and indomethacin)
from the dosage formulation.
Pharmacokinetic
Quantitative alterations in pharmacokinetic parameters(ADME)
resulting in abnormally high concentrations of the
drug at the site of action with consequent enhancement
of biological effects.
This is exemplified by the individual variation in
rates of microsomal oxidation due to genetic, biological
(eg, age and disease state), or environmental (eg,
dietary, pollutants, alcohol and other interacting
drugs) factors.
Pharmacodynamic
The organ or tissue responsiveness to toxic actions
might be elevated in some patients leading to ADRs.
RISK FACTORS
You are responsible for
all interactions with your state board.
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. Concurrent use of Multiple Medications (Polypharmacy)
Irrational prescribing
Inappropriate use
Insufficient monitoring of medications
Multiple medical conditions
Over prescribing
Frequent regimen changes
Self treatment
Lack of patient education
Age, Elderly patients receive an average of 3 to 5 prescriptions per day.
Adverse Drug Reactions (ADRs)-Definition 
