adverse drug reactions Flashcards
define adverse drug reaction
A response to a medicinal product, or combination of medicinal products, which is noxious and unintended (MHRA 2015)
unwanted or harmful reactions following the administration of drugs or combination of drugs under normal conditions of use and is suspected to be related to the drug
impacts of ADRs for patients
- reduced quality of life
- poor compliance
- reduced confidence in clinicians and the healthcare system
- unnecessary investigations or treatments
impacts of ADRs for the nHS
- Increased hospital admission
- Longer hospital stays
- GP appointments
- Inefficient use of medication
CLASSIFICATION OF ADRS
(Rawlins Thompson )
A
Augmented pharmalogical
B
Bizarre
C
Chronic/continuing
D
Delayed
E
End of use/withdrawal
F
Failure of treatment
G
Genetic
Describe type A augmented
most common
predictable
●Exaggerated effect of drugs pharmacology at a therapeutic dose
● Often not life threatening
● Dose dependent and reversible upon withdrawing the drug
describe type B Bizarre
- not related to pharmacology
- Not dose related
- Can cause serious illness or mortality
- Symptoms do not always resolve upon stopping drug
- not predictable
describe type C chronic/continuing
ADRS that continue after the drug has been stopped
describe type D delaye
ADRS that become apparent some time after stopping the drug
malignancies after immunosuppression
examples of type C
osteoporosis and steroids
describe type E end of use/withdrawal
ADR develops after the drug has been stopped
describe type F failiure of treatment
unexpected treatment failiure
could be due to drug to drug interaction or drug to food interaction
poor compliance with administration instructions
describe type G genetic
drug causes irreversible damage To genome
what is DoTS
an alternative way to classify ADRS
D
Dose relatedness
T
timing
S
Susceptibility
more complex but more detail
example of type F
failure of oral contraceptive pill in presence of enzyme inducer
when is DoTS more useful
Useful for those working in pharmacovigilance, undertaking research or developing medicines
3 categories of dose relatedness
hypersusceptibility
collateral effects
toxic effects
describe hypersusceptibility
ADRS at at subtherapeutic doses (eg anaphylaxis with penicillins)
describe collateral affects (side effects)
ADRs at therapeutic doses (eg hypokalaemia with loop diuretic)
describe toxic affects
ADRs at subpratherapeutic doses (eg
describe time dependent
adrs which can develop during any time during treatment
often due to clinical changes in the patient
categories of time dependent
rapid
first dose
early
intermediate
late
delayed 1
describe rapid
due to rapid administration
describe first dose
first dose only
describe early
occur early during treatment but resolve as treatment progresses
describe intermediate
occur after some delay
describe late
risk increases with prolonged or or repeated exposure
describe delayed
occur some time after exposure or after drug withdrawal
describe susceptibility
Certain patient groups/populations may have a specific susceptibility to ADRs from a drug
- Age (anticholinergics in elderly patients)
- Gender (metoclopramide in females)
- Disease states (eg diclofenac in CVD)
- Physiological states (eg phenytoin in pregnancy)
how are ADRs identified
- pre clinical testing
- clinical trial data
- post marketing surveillance
- pharmacovigilance
describe toxicity testing
Testing in animals before being given to humans
Long term administration in different species
Toxic doses given to identify likely ‘targets’ of toxic effects
Recovery studies aim to identify irreversible ADRs (e.g. carcinogenesis and
neurodegeneration)
Acceptable level of toxicity depends on intended indication
Findings may halt development of drug or provide focus for future trials
define side effects
an unintended effect of a drug related to its pharmacological properties and can include unexpected benefits of treatment
2 categories of severity of ADRs
mild
severe
3 examples of mild ADRs
nausea, drowsiness, itching rash
4 examples of severe ADRs
respiratory depression, neutropenia, catastrophic haemorrhage, anaphylaxis
what are the adverse reactions to beta blockers
Bradycardia and heart block are primary adverse effects
Bronchospasm is a secondary pharmacological adverse effect
3 causes of ADRs
Pharmaceutical variation
Receptor abnormality
Drug-drug interactions
4 times when to suspect an ADR
Symptoms soon after a new drug is started
Symptoms after a dosage increase
Symptoms disappear when the drug is stopped
Symptoms reappear when the drug is restarted
6 common ADRs
Confusion
Nausea
Balance problems
Diarrhoea
Constipation
Hypotension
describe the yellow card scheme
The first ADR reporting scheme
Collects spontaneous reports
Acts as an ‘early warning system’ for identification of previously unrecognised reactions
Provides information, about factors which predispose patients ADRs
Continual safety monitoring of a product throughout its life span as a therapeutic agent
4 critical pieces of info that need to be included on a yellow card
- Suspected drug
- Suspect reaction
- Patient details
- Reporter details
