NTA Level 6 • Semester 2 • PST06211

Introduction to Adverse Drug Reactions (ADRs)

Monitoring and Evaluation of Medicine Use • Source Session/Topic 12

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Session 12: Introduction to Adverse Drug Reactions (ADRs)

Total Session Time: 120 minutes

Prerequisites

• None

Learning Tasks

By the end of this session students are expected to be able to:

• Define ADRs

• Explain the predisposing factors for ADRs

• Classify ADRs

• Explain each class of ADRs

Resources Needed:

• Flip charts, marker pens, and masking tape

• Black/white board and chalk/whiteboard markers

• Computer and LCD Projector

SESSION OVERVIEW

Activity/

Step Time Content

Method

1 05 minutes Presentation Introduction to Learning Tasks

10 minutes Presentation

2 Definition of ADRS

Buzzing

3 20 minutes Presentation Predisposing Factors for ADRs

20 minutes Presentation

4 Classification of ADRS

Brainstorming

5 55minutes Presentation Explanations on each Class of ADRs

6 05 minutes Presentation Key Points

7 05 minutes Presentation Evaluation

PST 06211 Monitoring and Evaluation of Medicines Use NTA Level 6 Semester 2 Facilitator Guide

SESSION CONTENTS

STEP 1: Presentation of Session Title and Learning Tasks (5 minutes)

READ or ASK students to read the learning objectives and clarify

ASK students if they have any questions before continuing.

STEP 2: Definition of ADRS (10 minutes)

Activity: Buzzing (10 minutes)

ASK students to pair up and buzz on the following question

• What is Adverse drug reaction?

ALLOW few pairs to respond and let other pairs to add on points not mentioned

WRITE their response on the flip chart/board

CLARIFY and SUMMARIZE by using the content below

• Adverse drug reaction is a noxious and unintended reaction that occurs at a dose used for

the treatment, diagnosis and prevention of disease, disorder or syndrome.

• Side effects and ADRs are associated with drug use posing serious health consequences.

Sometimes the word side effect and ADR are used alternatively but there is a clear

difference between them. Side effect is often termed as type A ADR.

• Sid effect is also an undesirable effect of drug and comes under ADR.

STEP 3: Predisposing Factors for ADRs (20 minutes)

• Age:The incidence of adverse drug reaction appears to be highest in the very young and

very old people. In these two extreme periods of life, there is poorly developed and altered

physiological function respectively. Therefore, metabolism and elimination of some drugs

may be delayed.

• Pathophysiological conditions:Diseases may alter the pharmacokinetic handling of a drug,

its tissue sensitivity or the response to a drug. That is, diseases can alter drug absorption,

metabolism, elimination and the body‘s response to drugs.

• Amount of drug administered:An excessive response to drug or prolonged therapy may be

a predisposing factor for ADRs. Over dosage is often relative rather than absolute because

the individual response to a drug varies.

PST 06211 Monitoring and Evaluation of Medicines Use NTA Level 6 Semester 2 Facilitator Guide

• Sex:several studies have shown that for some drugs women are more likely to suffer from

ADRs than men. This is due to pharmacokinetic and or pharmacodynamic sex-related

factors.

• Previous history of allergy:Patients who have previously suffered an allergic drug reaction

appear to be more susceptible than others to allergic ADRs in general. Heredity may make

some people more susceptible to the toxic effects of certain drugs

• Racial or Genetic Factors: There may be racial differences in the incidence of some type

of ADRs or some individuals have a genetically determined response to development of

ADRs. e. g. Ethno-pharmacological difference such as glucose 6-phosphate dehydrogenise

deficiency, which predisposes to some drug induced haemolytic anaemia, is commoner

amongst Africans.

• Multiple Drug Therapy (Polypharmacy)

The incidence of ADRs increases with the number of drugs given due to risk of

interactions. Interaction between prescribed drugs is therefore an area, which is of concern

to every health care professional.

STEP 4: Classification of ADRS (20 minutes)

Activity: Buzzing (5 minutes)

ASK students to pair up and buzz on the following question for 2 minutes

• What are classes of adverse drug reactions?

ALLOW few pairs to respond and let other pairs to add on points not mentioned

WRITE their response on the flip chart/board

CLARIFY and SUMMARIZE by using the content below

• There are four basic systems used to classify ADRs

o Alphabetical or ABCDE system – by Rawlins and Thompson

o According to intensity

o Underlying mechanism mode

o ADR according to frequency

STEP 5: Explanations on each class of ADRs (55 minutes)

• ABCDE SYSTEM – classify ADRs into five types

o Type A („augmented―)

 These ADR are expected

PST 06211 Monitoring and Evaluation of Medicines Use NTA Level 6 Semester 2 Facilitator Guide

 They can be predicted on the base of pharmacodynamic properties of drug

 They depend on drug dose, they appear at higher doses

 Frequency is high > than 1%

 Mortality is low

 Therapy consists in dose adjustment

 e.g.: cough after ACEI, bleeding from GIT after

NSAIDs, aspirin, corticoids

o Type B (bizard―)

 Idiosyncratic reactions

 These ADR are not expected

 They can be hardly predicted

 Doesn´t depend on dose

 Occur in predisposed, intolerant patients – can be explained by rare genetic

polymorphism, allergic reactions

 Frequency is low < than 0,1%

 Mortality is high

o Type C continuous)

 This type of ADR increases number of ―spontaneous― diseases

 They occur usually after long-lasting administration

 They are often serious and persistent

 Mechanism of genesis is unclear

 They are unexpected, not predictable

 They can´t be verified experimentally

 e.g.: oral contraceptives and increased occurrence of thromboembolia.

o Type D (delayed)

 Adverse effect may be presented years after a drug was used (years resp.

generations)

 Teratogenity

 Carcinogenetic

 Mutagenity

 e.g.: cancer of vagina at daughters of mothers treated with diethylstilbestrol

o Type E (End of use)

 After therapy ending (syndrome from omitting i.e. Withdraw syndrome)

 Rebound phenomenon e.g.: beta blockers, opioids, corticosteroids, nitrates

Note: WHO in this system adds their sixth type which they referred to as type F

o Type F— (no response)

 Due to Failure of efficacy

 Caused by Resistance to antimicrobials

o ADR ACCORDING TO INTENSITY

 Mild – don´t require to stop or to change treatment

PST 06211 Monitoring and Evaluation of Medicines Use NTA Level 6 Semester 2 Facilitator Guide

 Moderate – require to change therapy, but don´t threat life of the patient

 Serious – death, hospitalization, teratogenity

o ACCORDING TO FREQUENCY

 Very common – when it is greater or equal to 1/10

 Common – when it is greater or equal to 1/100

 Uncommon – when it is greater or equal to 1/1,000

 Rare – when it is greater or equal to 1/10,000

 Very rare – when it is below 1/10000

o ACCORDING TO UNDERLYING MECHANISM MODE

 Intolerance – lower than usual dose produce anticipated response

 Idiosyncratic (―unusual‖) response – determined by genetic alteration, producing

response that is not anticipated

 Allergy – response modulated by immune system

 Pseudo allergy – reaction similar to allergy but not mediated by immune system

STEP 6: Key Points(5 minutes)

• Adverse drug reaction is a noxious and unintended reaction that occurs at a dose used for the

treatment, diagnosis and prevention of disease, disorder or syndrome.

• There are four basic systems used to classify ADRs, Alphabetical or ABCDE system ,

According to intensity, Underlying mechanism mode and ADR according to frequency

• predisposing factors for ADRs include age, Racial or Genetic Factors, Previous history of

allergy, Sex, Amount of drug administered and Pathophysiological conditions

STEP 7: Evaluation (5 minutes)

• What is ADRs?

• Classify ADRs?

• What are predisposing factors for ADRs?

PST 06211 Monitoring and Evaluation of Medicines Use NTA Level 6 Semester 2 Facilitator Guide

References

Quick, J. D. (1997). Managing drug supply the selection, procurement, distribution and use of

pharmaceuticals. West Hartford, CT: KumarianPress.Bartsch, S. (2007).

The Global Fund to Fight AIDS, Tuberculosis and Malaria. Global Health Governance and the

Fight Against HIV/AIDS,146-171. doi:10.1057/9780230591349

WHO Operational package for assessing, monitoring and evaluating country pharmaceutical

situations. (2015, November 20). Retrieved from

https://www.who.int/medicines/publications/WHO_TCM_2007.2/en/

PST 06211 Monitoring and Evaluation of Medicines Use NTA Level 6 Semester 2 Facilitator Guide

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