Drug Safety and Side Effects Flashcards
ADRs are classified into type A and B
What is type A?
Most common type of ADR
Consequence of drug action, often dose dependent
Can be resolved by lowering dose or withdrawing treatment
Generally picked up and understood during drug testing
Give examples of type A ADRs for NSAIDS, diuretics, opioids, DM drugs
NSAIDS: GI bleeds, peptic ulcer, renal impairment, bronchospasm
Diuretics: hypotension, dehydration, electrolyte changes
Opioids: vomiting, confusion, constipation, urinary retention, resp depression (OD) due to opiate receptor stimulation
Insulin/ hypoglycaemic drugs: hypoglycaemia. Due to poor control of blood glucose, excess glucose uptake, storage
All these ADRs are predictable due to drug moa
ADRs are classified into type A and B
What is type B?
Type B – idiosyncratic or bizarre
Rare, not dose related, may be fatal
Unrelated to known drug moa so hard to predict
Often involves immune system/genetics
Need to withdraw drug – do not use again
Hypersensitivity, anaphylaxis or SJS= life threatening
Need longer term + widespread use in pop to identify, so pharmacovigilance is vital
How do drugs induce hypersensitivity reactions?
Penicillin on its own is small, non immunogenic.
Pencillin when it combines w plasma protein, it forms a hapten molecule - which triggers immune response.
Leads to mast cells releasing histamine and anaphylaxis
Can we get ARDs due to chronic drug taking?
Some drugs must be taken long term, indefinitely e.g., Corticosteroids for arthritis, Lupus, IBS
This leads to long term ADRs
What are options for reducing ADRs?
Minor Type A: continue to treat, and then treat the ADR w otra drug eg laxatives for opioid constipation
‘Accept’ more severe ADRs – risk vs potential therapeutic effect eg alopecia w chemo
Be aware of vulnerable groups and drugs likely to cause interactions!
Good drug history essential
Keep up to date with drug info (e.g., BNF)
HCW report problems asap (pharmacovigilance)
Pharmacovigilance in the UK involves:
Yellow card
Black triangle
Green form
Compare them:
Yellow cards= post-marketing surveillance (good) - Anyone can make a report (good)
However:…
Gross under-reporting suspected
Numerator data: only those that suffer ADR fill in the form
No denominator data: unsure how much of the pop are taking this drug at one time, to find the severity/incidence of an ADR.
Need to monitor black triangle ones closely
The Green Form is a reporting form used by healthcare professionals to report suspected side effects or adverse reactions associated with vaccines. It is primarily focused on vaccine safety monitoring and surveillance. The form helps in collecting data on vaccine-related adverse events.
Changes in drug absorption, distribution, metabolism, excretion (ADME)
lead to profound effects on drug action
Describe how diuretics can cause ADRs
Diuretics, e.g., thiazides reduce Li excretion (used to treat BPD)
Raises plasma lithium levels which need to be kept in target range!
Li toxicity can lead to confusion, anorexia etc.
When beta-blockers work on lung tissue, they cause the airways to narrow or contract–> SOB, dyspnea, wheezing
Diazepam and alcohol are both CNS depressants, so mixing them can be fatal
Grapefruit juice can block intestinal CYP3A4, so instead of being metabolized, more of the drug stays in the body longer= risk of bleeding in warfarin.
