adverse drug reactions

Question 1

what are the consequences of side effects?

Answer 1

• makes patients less keen to take their medications
• reduces available choice of drug treatment
• reduces quality of life
• reduces patients confidence in HCPs

some side effects may be beneficial (eg. the sedative effect of antihistamines may be beneficial to the itch). However, they are useually harmful.

Question 2

define adverse drug reaction (WHO)

Answer 2

a response to a drug which is noxious and unintended and which occurs at doses normally used in man for the prophylaxis, diagnosis or therapy of disease or for the modification of physiological function.

The new EMA definition of adverse reaction includes adverse effects in uses outside terms of marketing authorisation including

• Misuse and abuse
• Medication error - these are preventable
• Overdose
• Occupational exposure

Question 3

outline the traditional classification of adverse drug reactions

Answer 3

type A reaction - sometimes referred to as augmented reactions which are dose dependant and predictable by the pharmacology of the drug.

type B - bizzare reactions - idiosyncratic and not predictable on the basic of pharmacology

Question 4

what is the alternative (DoTS) classification of adverse reactions?

Answer 4

dependant on:

• dose of drug
• time course of reaction
• susceptibility factors

Question 5

what is predictive remodelling?

Answer 5

we can target drug therapy to patients through predictive remodelling which says who is statistically more likely to benefit and who is at the greatest risk of an ADR. It takes into account

• age
• genetics
• sex
• physiological state (eg. pregnancy)
• exogenous drugs or food
• disease

Question 6

why can detecting ADRs be difficult?

Answer 6

• reactions are rare
• they may be treated like an illness
• reactions are novel
• reactions may be delayed
• the reactions may affect offspring

Question 7

How can you diagnose adverse drug reactions?

Answer 7

They may emulate traditional diseases and may present in different ways.
You therefore need to decide that it is the drug:
- challenge - did the reaction start at or after the start of treatment
- de-challenge - did the reaction stop when the treatment was stopped?
- re-challenge - did the reaction start again when the medication was restarted?
- is there any other alternative causes for the reaction?

Question 8

how do you deal with adverse drug reactions?

Answer 8

1. deal with the cause - stop, pause or reduce the dose of the suspected drug
2. consider why the drug therapy was prescribed and what alternate therapy can be offered
3. treat symptoms where possible

sometimes there a specific ‘antidote’ treatments that can be used

Question 9

what is pharmacovigilance?

Answer 9

The science and activities relating to the detection, assessment, understanding and prevention of adverse effects or any other drug related problem.
This supports the public health programmes by providing reliable, balanced information for effective assessment of risk-benefit of medicines over product lifetime.

Question 10

what is the yellow card scheme?

Answer 10

a scheme in which you can voluntarily, confidentially and anonymously report ADRs. There is still however a significant amount of underreporting. Anyone can report and anything can be reported but there is a significant focus on serious or harmful ADRs as well as those for new drugs or vaccines which are marked by a black upside down tringle symbol.

Question 11

apart from the yellow card scheme, what other approaches do we have to pharmacoviggelance?

Answer 11

case reports in scientific literature 
cohort studies 
case control studies 
disease (drug therapy) registers
record linkage schemes