Adverse Drug Reactions Flashcards
What is an ADR?
adverse drug reaction
What are the types of ADR?
type A type B type C type D type E
What is type A adverse drug reaction?
is an augmented/exaggerated pharmacological action
is dose related
occurs in everybody = effects can be expected a too high of a dose is taken
predictable effects
most have pharmacokinetic basis = ADME
some have pharmacodynamic basis - what the drug does to the body
What is type B adverse drug reaction?
is a bizarre/unexpected reaction
unexpected reaction from known drug actions
occurs only in some people
not dose related
- can be allergic or inherited
What are features of type B allergic reactions?
no relation to the usual pharmacological effects of the drug
often a delay between the first exposure to the drug and the occurrence of the subsequent adverse reaction
- ADR may not occur with the first dose
no formal dose-response curve, and very small doses of the drug may elicit the reaction once allergy is established
- ADR is not affected by dosage, the smallest amount can cause an ADR
the reaction disappears on discontinuation of the drug
illness is often recognisable as a form of immunological reaction
- rash, anaphylaxis, asthma
What is type C adverse drug reaction?
continuous long term administration
- some side effects/ADRs only occur after long term use
NSAIDS can cause analgesic nepropathy
- kidney function deterioates
What is type D adverse drug reaction?
delayed
- may occur after a few years or in the foetus/children
- takes time to develop
teratogenesis - birth defects
carcinogenesis - cause cancer
What is type E adverse drug reaction?
ending of use reaction = withdrawal
- must be gradually reduced to allow the body to rebuild
How can ADRs be caused/related to dose?
ADR that occur at doses above the therapeutic dose range (e.g. bleeding with warfarin)
ADR that occur at doses within the therapeutic range (e.g. anticholinergic effects of tricyclic antidepressants).
ADR that occur at doses below therapeutic range are called hypersensitivity reactions (e.g. penicillin allergy)
How can ADRs be caused/related to time/duration?
ADRs that are independent of the duration of therapy
Rapid reactions occur when a drug is infused too rapidly
First dose reactions occur after the first dose of a course of treatment and not necessarily thereafter
Early reactions occur early in treatment then abate (stop) with continuing treatment
Intermediate reactions occur after some delay
Late reactions occur rarely or not at all at first, but the risk increases with continued or repeated exposure
Withdrawal reaction
Delayed reactions
How can ADRs be caused/related to susceptibility?
ADRs do not affect us all equally
Genetic susceptibility Age (both children and elderly) Sex Physiological changes (e.g. pregnancy) Diseases (Renal or hepatic insufficiency) Other factors (e.g. drug interactions)
How can ADRs be caused/related to predisposing factors?
Renal or liver failure
- prescription and appearance indicators
Disease states
- COPD develop bronchoconstriction with βblockers
Previous ADR
Allergy history
Other drugs
- drug interactions
What should be done in practice when an ADR is detected?
abrupt withdrawal of the drug
prescribe an antidote
- anti-histamine
talk to patient and check medical notes
What drugs are most likely to cause ADRs?
Drugs with NTI Digoxin Phenytoin Theophylline Aminoglycosides Cytotoxics
What is the yellow card scheme? Who can report on it? What should be included? What does not need to be included?
voluntary method of reporting ADRs
- for new drugs = all suspected ADRs should be reported
- for established drugs and vaccines = only serious (life threatening) ADRs
- doctors, dentists, coroners, pharmacists and nurses should report suspected ADR.
- patients and carers can self-report as well
all therapeutic agents are included in the scheme
does not require patient consent or patient details
is not a legal requirement
