ADVERSE DRUG REACTIONS:
A response to a drug which is noxious &
Unintended & which occurs at normal doses used
ADVERSE DRUG EVENTS:
Any untoward medical occurance that may present
during treatment with a pharmaceutical
product(drug),but which does not necessarily have
a causal relationship with this treatment.
⦁ WHO defined it as the “science & activities related
to the detection, assessment, understanding &
prevention of adverse effects or any other drug
⦁ The information generated by pharmacovigilance is
useful in educating doctors about ADRs & in the
official regulation of drug use.
⦁ It has important role in rational use of medicines &
assessing safety of medicines.
ADRs can be minimised but not eliminated by
observing the following practices:
Avoid all inappropriate use of drugs in the context
of patient’s clinical condition.
Use correct dose,route & frequency of drug
administration based on patient’s specific
Take into consideration about previous history of
drug reactions,allergic diseases &exercise
caution(drug allergy is more common in allergic
Rule out possibility of drug interactions when
more than one drug is prescribed.
Adopt correct drug administration technique
(eg:iv inj of vancomycin must be slow).
Carry out appropriate laboratory monitoring
(serum drug levels with lithium).
SEVERITY OF ADVERSE DRUG REACTIONS:
Minor:No therapy,antidode or prolongation of
hospitalization is required.
Moderate:Requires change in drug therapy,specific
treatment or prolongs hospital stay atleast one
Severe:Potentially life threatening,causes
permanent damage/requires intensive medical
Lethal:Directly/indirectly contributes to death of
Adverse drug effects may be categorized into:
Unwanted & unavoidable p’dynamic effects occurs at
Reduction of dose generally ameliorates the symptoms.
Side effects may be based on same action as the therapeutic
eg; Atropine is used as preanaesthetic for its antisecretory
action,the same action produces dryness of mouth as side
Many drugs have been developed from observation of side
eg; sulfonamides (antibacterial) used as hypoglycemic
⦁ These are indirect consequences of a primary
action of drug.
Eg;corticosteroids weekens host defence
mechanisms so that latent TB gets activated.
⦁ Due to excessive p’cological action of the drug
due to overdose & prolonged use.
⦁ The effects are predictable & dose related.
⦁ They result from functional alteration(high dose of
ATROPINE causes DELIRIUM)or drug induced tissue
damage(Hepatic necrosis from PARACETAMOL
⦁ Due to large doses of drugs.
⦁ Poison endangers life by severely affecting one or more vital
Resuscitation & maintenance of vital functions: Adequate
ventilation,artificial respiration, maintenance of BP, heart
beat, body temperature & blood sugar level.
Termination of exposure:
Removing patient to fresh air,washing skin & eyes,induction of
emesis with syrup ipecac/gastric lavage [avoided in kerosine &
Prevention of absorption of ingested poisons:
20-40g(1g/kg) of activated charcoal suspension
should be administered in 200ml of water.
Strong acids& alkalies,metallic salts,iodine,
cyanides,alcohol,organic solvents are not adsorbed by
Quick removal of poison from the body by
haemodialysis,inducing diuresis/altering urinary
known as inability to withstand/consume the drug.
Eg; only few doses of carbamazepine may cause ataxia in
It is genitically determined abnormal reactivity to a chemical.
Peculiar to an individual because the drug reacts with the
specific gene which is specific to an individual.
Eg; Barbiturates causes excitement & mental
confusion in some individuals.
⦁ A medical condition that makes a individual to feel ill
when a drug is taken.
⦁ Allergic reactions occur only in a small proportion of the
population exposed to the drug & cannot be produced in other
⦁ Occur even with smaller doses & have a different time
course of onset & duration,also called as
HYPERSENSITIVITY but not supersensitivity.
⦁ The drug/its metabolites acts as AG/HAPTEN & induce
production of AB/sensitized lymphocytes.
⦁ They are of two types: HUMORAL & CELLMEDIATED.
On exposure to the drug,AG:AB reaction takes place on the
mast cell surface releasing mediators like
histamine,5HT,leukotrienes Prostaglandins etc.,resulting in
itching, angioedema, bronchospasm, rhinitis.
Drug+component of a specific tissue cells act as AG.The
resulting antibodies(IgG,IgM)bind to the target cells on
reexposure AG:AB reaction takes place on the surface of these
cells,complement is activated and cytolysis occurs.
AG:AB complexes bind complement & precipitate on
vascular endothelium giving rise to a destructive inflammatory
Manifestations are rashes, serum sickness, mental symptoms,
myocarditis, nephritis(usually in 1-2weeks)
These are mediated through production of sensitized T-
lymphocytes carrying receptors for the AG.They form
takes>12hrs to develop.
Administration of oxygen.
0.5mg adrenaline i.m injection.
Administer a H1 antihistaminic i.m/slow i.v.
I.V of glucocorticoids should be added in many
Adrenaline followed by a short course of
glucocorticoids is indicated for bronchospasm
attending drug hypersensitivity.
Glucocorticoids are the only drug in type II,III,IV
It is a cutaneous reaction resulting from drug
induced sensitization of the skin to Uvrays.the
reactions are of two types:
Drugs/its metabolites accumulates in the
skin,absorbs light & undergoes a photochemical
reaction followed by a photobiological reaction
resulting in local tissue
damage.[edema,blistering etc drugs involved are
Rarely AB mediate photoallergy & the
reaction takes form of flare&wheal on exposure
to sun drugs involved are
It is a state in which use of drugs for personal
satisfaction is accorded a higher priority than
other basic needs,often in the face of known risks
a].Psychological dependance:individual believes
optimal state of wellbeing is achieved only
through the actions of the
b].Physical dependance:an altered physiological
state produced by repeated administration of a
drug which necessitates the continued presence
of the drug to maintain physiological equilibrium.
Discontinuation of the drug leads to withdrawl
c].Drug abuse:social disapproval of the manner
& purpose of drug use.
d].Drug addiction:strong physiological &
psycological dependence on a drug.
e].Drug habituation:a psychological dependence
on drug due to repeated consumption with a
desire to continue its use,withdrawal produces
only mild discomfort.
9).Drug withdrawal reactions:
These reactions are produced when there
is sudden cessation of the drug or
interruption of therapy with certain other
Eg;precipitation of MI may result from stoppage
of beta blockers.
It refers to capacity of a drug to cause
foetal abnormalities when administered to the
Eg; Warfarindepressed nose,growth
11).Mutagenicity & Carcinogenicity:
The capacity of a drug to cause genitic defects
Usually oxidation of the drug results in the
production of reactive intermediates which effects
genes & may cause structural changes in the
Eg; anticancer drugs, tobacco, estrogens, radioisotopes.
12).Drug induced diseases:
These are iatrogenic(physician induced)diseases
& functional distrubances(disease)caused by drugs
which persists even after the offending drug has
been withdrawn & largely eliminated.
eg:peptic ulcer by salicylates & corticosteroids.