adverse drug reactions Flashcards
how to classify ADRs
based on onset, severity, and type
onset- time of acute, subacute and latent
acute within an hour (eg anaphylaxis), sub-acute (1-24 hrs), latent after 2 days
severity-mild, moderate, and severe
mild requires no change, moderate does+hospitalisation, and severe can be life-threatening
type A with examples
AUGMENTED: most common- predictable and dose dependent eg NSAIDS and ulcers, or anticholingergics and dry mouth
DIAGRAM ADR in paracetamol vs digoxin
digoxin ADR linear- paracetamol usually harmless, until suddenly effects become toxic
type B reactions
BIZARRE: rare and unpredictable- often immunological reactions causing allergy/pseudoallergies
type C reactions
caused by CHRONIC use, which leads to accumulation of drugs eg methotrexate and fibrosis of liver
type D
DELAYED effects, which can be carcinogenic eg immunosurpressants
type E- different type
END (E=end) of treatment-either withdrawal reactions (problems when stop taking drug) or rebound reactions (situation gets worse when drug stopped)
example of rebound reations
when taking clonidine, BP goes down, but when stopped, BP goes up even higher
examples of pseudoallergies ie not really allergies
NSAIDS lead to bronchospasm, ACE inhibitors lead to cough/angioedema (swelling of lips)
common drugs causing ADRS
antibiotics, anticoagulants, CVS drugs, NSAIDS, CNS drugs
problem with ADR detection
rare events often not detected until drug is licensed
yellow card scheme
way for clinicians reporting any adverse drug reactions for new drugs, and SERIOUS ADRS for common drugs
types of drug interactions
pharmacodynamic (drugs effect on body ie competing for receptora), pharmacokinetics (body’s effect on drug eg absorption/metabolism), and pharmaceutical (interaction of drugs outside body)
pharmacodynamic interactions- types
can be additive effect eg ethanol and benzodiazepines or antagonist eg anticholingergic
types of pharmacokinetic interactions- change in absoprtion- CHELATION wit example
drugs bind together= less absorption eg antibiotics
types of pharmacokinetic- protein binding interactions and importance, with example
drugs compete for plasma proteins- often not important but eg warfarin
types of pharmacokinetic- difference metabolism+ CYP450 inhibitor examples
multiple drugs compete for same P450 enzymes, particularly when given a CYP450 inhibitor eg antibiotics+ HIV drugs
CYP450 inducers
rifampicin and St johns wort
most important P450 enzyme
CYP450 3A4
inducers vs inhibitors
inhibition rapid vs inducers longer (as takes time to make new Cyp450 enzymes)
types of pharmacokinetic- elimination reactions with examples
occurs in renal tubule- pencillin leads to more elimination, lithium leads to less
