Adverse Drug reactions Flashcards
What is the frequency of ADRs in hospital in patients
10-20%
What is the 3 onsets for ADRs and their timings
acute - 60mins
sub-acute - within 24hrs
latent - >2days
what is the severity of ADRs range from
Mild requiring - no change in therapy
Moderate - additional therapy
severity - life threatening / disabling
What is the classification of ADRs divided into
Type A Augmented Type B Bizarre Type C Chronic Type D Delayed Type E End of treatment Type F Failure of treatment
What are the features of a type A reaction
predictable
dose dependant
resolved when drug therapy is stopped
what are the reasons for type A reaction
Too high a dose
Pharmaceutical variation
Pharmacokinetic variation
Pharmacodynamic variation
In type A reactions what factor in the ADMEs result in the greatest therapeutic failure
absorption
What effects absorption
Gut motility
formulation
first pass metabolism
dose
What condition can effect absorption from the gut
oedema
Why is liver disease particularly important when considering drug therapy
Has a very narrow therapeutic index
What two factors need to be considered in the elimination of drug therapies and why?
If patient has renal impairment or a reduced glomerular filtrate rate, these two factors in drug therapy can result in increased toxicity
What is the outcome if a patient is a slow metaboliser
metabolise drugs by acetylation therefore more prone to drug toxicity
What is the secondary effect of type A reactions
when ADRs is not related to the therapeutic effect of the drug
What is an example of a pharmogenetic variation
isoniazid used to treat tuberculosis can induces peripheral neuropathy in some people
What is the result of cardiac failure with regards to ADR
Oedema prevents absorption from the gut
poor renal perfusion and decreased GFR
Hepatic congestion
What is the features of type B ADRS
rare
unpredictable
unidentified
What is the immunological features of type B ADRs
No relation to the pharmacological action of the drug
Delay between exposure and ADR
No dose response curve
Manifests as rash, asthma, serum sickness
What are some important factors in type B ADRs
More common with macromolecules
Patients with asthma and eczema
Patients HLA status
What are the features of type C ADRs
semi predictable
related to duration of treatment as well as dose
not due to single dose
Example of chronic ADRs
steroid dependancy eg coristol steroid
opiate dependancy
antipsychotic medications
What is the features of type D ADRs
Can occur a long time since treatment has been given in the patient or the patients children
Give an example of a type D ADRs affecting a patient child
Tetratogeneic agents e.g. phalidamide disrupt growth of fetus
What causes type E ADRs
sudden stop of treatment following long term use resulting in rebound phenomena
Examples of drugs causing rebound phenomena
Steroids - addisonian
beta blockers - unstable angina
alcohol - withdrawal seizures
How are ADRs diagnosed
differential diagnosis
past medical history
time of onset and drug dosage
lab investigations
