4: Adverse drug reactions Flashcards
What is an adverse drug reaction?
Illness caused by medication
What’s the difference between a side effect and an adverse drug reaction?
Side effects are caused by normal doses; subset of ADR (which may be caused by inappropriate doses e.g digoxin toxicity)
Which group of patients commonly suffer ADRs?
Elderly
Those with co-morbidities
Those on loads of drugs already
What is the therapeutic index of a drug?
Space between effective dose and toxic dose
The greater the therapeutic index of a drug, the ___ it is.
safer
and vice versa
How is therapeutic index calculated?
Therapeutic index = Toxic dose / Effective dose
Which enzyme family usually metabolises drugs in the liver?
CYP450
Where are most drugs excreted?
Bile
Urine
What process usually goes wrong to cause an ADR?
CYP450 - oxidation, reduction or hydrolysis
What are
Type A
Type B
ADRs?
Type A - predictable, dose-dependent reactions
Type B - unpredictable, dose-indepedent (weird reactions)
What is a
Type C
Type D
Type E
ADR?
Type C - chronic reactions
Type D - delayed reactions
Type E - reactions seen when the drug is withdrawn
What is a Type A ADR?
Predictable, dose-dependent reaction
What type of ADR is dehydration associated with diuretic overdose?
Type A
What type of ADR is ischaemic nephropathy associated with ACE inhibitor use during acute illness in someone with kidney disease?
Type A
What antibiotic has a very low therapeutic index?
What does it damage in toxic doses?
Gentamicin
CN VIII, kidney tubules
What can different drugs do to cause a Type A ADR?
Interact with one another
Where can you find drug interactions before prescribing them for patients?
BNF
Which family of antibiotics cause drug interactions?
Macrolides
(e.g azithromycin, clarithromycin, erythromycin)
WITH theophylline, statins
What is a common
a) side effect
b) interaction
of ACE inhibitors?
a) Dry cough
b) Amplify hypoglycaemia caused by sulphonylureas
What should you always ask about when taking a drug history?
Why?
Medication
OTC drugs
Herbal remedies
Because they may interact with certain drugs
Patients with which disorder have an increased risk of drug-induced confusion?
Parkinson’s
Which cardio condition can NSAIDs exacerbate?
Heart failure
Anticholinergic drugs may cause which renal condition in men with BPH?
Urine retention
because they constrict the ureters (usually used to TREAT incontinence)
Which drugs commonly exacerbate constipation?
Calcium
Anticholinergics
CCBs
Which drugs classically exacerbate asthma?
Why?
Beta blockers
may non-selectively BLOCK beta2 adrenoceptors
Foods which are rich in potassium interact with which drugs?
ACE inhibitors
ARBs
Spironolactone and eplerenone
Foods rich in Vitamin K interact with which drug?
Warfarin
What electrolyte should be restricted in those on ACE inhibitors, ARBs and K-sparing diuretics?
Potassium
bananas!!!
What is a Type B ADR?
Dose-independent, unpredictable reactions
Out of Type A and Type B, which ADR is more dangerous?
Type B
What is a derm presentation of potentially any drug?
Rash
What is a haem presentation of potentially any drug?
Bone marrow suppression
What is a Type C ADR?
Chronic, predictable drug reaction
Long term steroid therapy can cause which ADRs?
Cushing’s
Osteoporosis
Long term beta blocker use can cause which disease?
Diabetes
What is a Type D ADR?
Delayed reaction
not the same as chronic, often many years after stopping
What kinds of disease are caused by Type D ADR?
Congenital malformations, growth/developmental delay - teratogenic drugs
Malignancy - carcinogenic drugs
What treatments FOR cancer can cause cancer?
Radiotherapy
Chemotherapy
Phototherapy
What is a Type E ADR brought on by abruptly stopping beta blockers?
Rebound tachycardia
What is a Type E ADR brought on by abruptly stopping long-term steroids?
Addison’s (disease or crisis)
What is found next to newly licensed drugs (which may have ADRs) in the BNF?
Black triangle
How do you report ADRs of drugs?
Yellow Card
