Classification Of ADRs

Classification of ADRs

ADRs are classified into

1)extended Rawlins and Thompson classification

For detail of this click here

2)Dots classification

Dots classification of ADRs:

There are 3 types of Dots classification

A)on the basis of dose relatedness

B)on the basis of Time course of ADRs

C)on the basis of susceptibility

A) Dose relatedness:

In dose relatedness ADRs are classified into 3 different classes

1)toxic reactions

2)collateral reactions

3)hyper susceptibility reactions

1) Toxic Reactions:

•exaggerated pharmacological action of drug occur at toxic doses


•Toxic doses of antibiotics cause severe GI infection

•toxic doses of CCB cause severe headache

Management of Toxic reactions:

Reduce the dose , duration of drug

2) Collateral reactions:

most common

•occur at Normal doses


•non selective BB (normal dose) cause bronchoconstriction in lungs.

How Tricyclic antidepressants cause dry mouth?

•Tricyclic antidepressants (TCAD) block M3 receptor in salivary gland and cause xerostomia (dry mouth)* classification of ADRs 

Management of collateral reactions:

can’t manage easily

•Reasure the patient

•You can’t avoid it because occur at normal doses tolerate it.

•Do the symptomatic management

•Change the therapy if alternative therapy is present.

3) Hyper susceptibility reactions:

•occur at sub therapeutic doses

•include all hyper susceptibility reactions

Example of hyper susceptibility reactions:

• haemolytic anaemia

•idiosyncratic reactions

Management of hyper susceptibility reactions:

withdraw the drug product

•avoid re exposure

B) Time course of ADRs:

On the basis of time course ADRs are classified into 6 types

1)Rapid ADRs

2)First dose ADRs

3)early ADRs

4)intermediate ADRs

5)Late ADRs

6)Delayed ADRs

1) Rapid ADRs:

Rapid ADRs occur due to rapid administration of drug , some drugs should be administered slowly.

Examples of Rapid ADRs:

Redmen syndrome and anaphylactoid caused by rapid infussion of vancomycin injection.

How redmen syndrome and anaphyactoid is caused ?

Direct release of histamine by rapid vancomycin administration in whole body i.e. brain, stomach , vessels.

What is anaphylactoid reaction ?

Same as anaphylaxis in clinical features but immune system is not involved but histamine is involved.* classification of ADRs 

Management of Rapid ADRs:

•drug should be infuse slowly

2) First dose ADRs:

Appear after first dose of administration do not occur afterward.

Examples of first dose ADRs:

ACEIs and alpha 1 blockers cause orthostatic hypotension.

Management of first dose ADRs:

Care should be taken while taking first dose of drug.

3) Early ADRs:

Occur in early course of therapy,  occur initially for some days but then subside by the concurrent administration.

Examples of early ADRs:

•CCB and nitroglycerine cause severe headache at the course of time but later the patient become tolerant.

•Nifedipine cause persistent ankle oedema which remains throughout the course of time.* classification of ADRs 

4) Intermediate ADRs:

Which occur after some time of the treatment but their chances are reduced with the continuation of the therapy.

Either are hypersusceptibility or collateral reactions.

Examples of intermediate ADRs:

Venous thromboembolism (VTE) by the use of antipsychotic drugs.

5) Late ADRs:

Develop late as compared to intermediate,  occur after some time and its chances increase with continuous therapy and repeated exposure of drug.

They rarely occur or not occur at all.

Examples of Late ADRs:

•PPIs cause cancer or bone fracture.

•Opium cause opiate withdrawal syndrome

6) Delayed ADRs:

Develop late , occur even when the drug is withdrawn,  sometimes they are due to the withdrawal of the drug

Examples of delayed ADRs:

Vaginal adenocarcinoma caused by DES daughters. 

C) susceptibility ADRs:

Risk of ADRs vary between individuals.

Classified on the basis of







Those who are extreme of age are at the greater risk of developing ADRs.

New-borns, neonates,  infant are at the greater risk of developing ADRs.

Because in these there are no proper development of metabolic organ and excretory organ. Drugs will remain for higher time in the body.* classification of ADRs 


Females are at greater risk of developing ADRs as compared to males. Because in females water content is low and fat content is high as compared to males.

In females CYP3A4 is low than males , which metabolize 50% of clinically significant drug , so in females metabolism is low drug remain for higher time in the body.* classification of ADRs 


Different chronic diseases such as chronic kidney disease,  liver disease,  heart disease and patient taking different drugs (polypharmcy) are at the greater risk of developing ADRs and dose adjustment is required.


Occurs due to genetic variation.

CYP2C9*1 = wild type in European

CYP2C9*2 = variant type in Asian (poor metabolizer)

Due to this dose of warfarin is change in Asians and Europeans. 


The study of differences in drug response due to variation in genetic composition of individuals is known as pharmacogenetics .

Some individuals are  sensitive to pencillin and some are not due to differences in genetic composition.

Pharmacogenomic : the study of differences in drug response due to difference in genome.* classification of ADRs 

Learn more 

Searching Tags 

Classification of adverse drug reactions 

Types of ADRs 

Dots classification of ADRs 

Extended Rawlins and Thompson classification of ADRs 

Classification on the basis of dose relatedness

Classification Of Adverse Drug Reactions (ADRs)

Classification on the basis of time course of ADRs 

Classification on the basis of susceptibility 

What is toxic ADRs ?

What is collateral ADRs?

Adverse drug reactions (ADRs)

What is hyper susceptibility ADRs?

What is rapid ADRs?

What is first dose ADRs?

What is early ADRs?

What is intermediate ADRs?

What is late ADRs?

What is delayed ADRs?

Post a Comment