ADRs Flashcards
What is an adverse drug reaction?
unwanted or harmful reaction following administration of a drug or combination of drugs under normal conditions of use and is suspected to be related to the drug
give examples of mild ADRs
nausea
rash
drowsiness
give examples of serious ADRs
respiratory depression
neutropenia
catastrophic haemorrhage
anaphylaxis
Why are ADRs important?
5th commonest cause of hospital death majority are preventable affects pt's quality of life pts lose confidence in their doctors increases cost of pt care prevent drugs being used in pts may mimic disease cause hospital admissions
What is the Rawlins Thompson classification?
Augmented Bizarre/idiosyncratic Chronic Delayed End of treatment
What are the causes of ADRs?
pharmaceutical variation receptor abnormality abnormal biological system unmasked by a drug abnormalities in drug metabolism immunological drug to drug interactions multifactorial
Explain what an augmented drug reaction is
predictable
dose dependent
common
extension of primary effect or a secondary effect of the drug
Give examples of an augmented drug reaction
bradycardia and propanolol
hypoglycaemia and insulin
haemorrhage and anticoagulants
secondary effect - bronchospasm with beta blockers
Explain what a bizarre reaction is
not predictable not dose dependent cannot be readily reversed less common but often serious can be either idiosyncrasy or allergy/anaphylaxis
Give examples of bizarre reactions
penicillin and anaphylaxis
What is idiosyncrasy?
inherent abnormal response to a drug
Give examples of types of iodiosyncrasy
enzyme deficiency
receptor abnormality
Give an example of an enzyme deficiency that causes an idiosyncratic reaction
haemolysis with primaquine
due to G6PD deficiency (glucose 6 phosphate dehydrogenase)
Give an example of a receptor abnormality that causes an idiosyncratic reaction
malignant hyperpyrexia with GA
this is a drastic and sustained rise in body temperature
Explain how allergy to a drug develops
first dose acts as an antigen
then Ab is produced
second dose is an Ag-Ab reaction
What are the types of hypersensitivity reaction?
type 1 - immediate anaphylactic IgE mediated
type 2 - Cytotoxic, antibody-dependent IgM or IgG (Complement) MAC
type 3 - Immune complex disease
type 4 - delayed hypersensitivity T cell mediated
Give examples of a chronic type ADR
steroids and osteoporosis
analgesic nephropathy
steroids an iatrogenic Cushings syndrome
colonic dysfunction due to laxatives
Give examples of delayed ADRs
teratogensis - eg drugs taken in the first trimester - thalidomide
carcinogenesis - cyclophosphamide (chemo and immunosupressant) can cause bladder cancer
Give an example of end treatment ADRs
abrupt withdrawal of glucocorticoids leads to adrenocortical insufficiency
withdrawal seizures when anti-convulsants are stopped
What are the pt risk factors for ADRs?
gender (W>M) elderly neonates polypharmacy genetic predisposition hypersensitivity/allergies hepatic/ renal impairment adherence problems
What are the drug risk factors for ADRs?
steep-dose response curve
low therapeutic index
Give examples of prescriber risks for ADRs
prescription errors erroneous medical decisions ommissions in the prescription poor handwriting inadequate knowledge inadequate communication between HCWs
What are the suggestions that an ADR is occurring?
symptoms soon after a new drug is started
symptoms after a dosage increase
symptoms disappear when the drug is stopped
symptoms reappear when the drug is restated
What are the most common drugs to have ADRs?
antibiotics eg penicillin anti-neoplastics cardiovascular drugs hypoglycaemics eg insulin NSAIDs CNS drugs
What are the most common systems to be affected by an ADR?
GI Renal Haemorrhagic metabolic endocrine dermatological
What are common drug reactions?
confusion diarrhoea nausea constipation balance problems hypotension
How can ADRs be avoided?
give appropriate meds
don’t give unnecessary meds
check for interactions
report ADRs
What does the Medicines and Healthcare products regulatory agency do?
- approves medicines and devices for use
- watches over the medicines and devices and takes actions eg drug withdrawal to protect the public if there is a problem
What is the yellow card scheme?
ADR reporting scheme
collects spontaneous reports
collects suspected drug reactions
voluntary reporting
What are the strengths of the yellow card scheme?
Acts as an early warning system for identification of previously unrecognised ADRs
provides info about which factors predispose to ADRs
allows comparison of ADR profiles between products in the same therapeutic class, so could use another drug instead if found to be safer
continual safety monitoring
cheap to operate
rapid
readily accessible
can be applied widely and throughout a drugs use
What are the weaknesses of yellow card reporting?
cannot provide estimate of risk as number of cases is underestimated and total number of pts exposed is unknown
ADR may not be recognised
ADRs may not be reported
reporting increases when there is a new drug and decreases over time
Why are ADR reporting rates low?
- people not sure how to report
- people don’t want to be foolish as to incorrectly identifying an ADR
- people do not want to expose themselves to legal liability/ don’t want to admit harm caused
- people too busy to report ADR
- people believe that only safe drugs are used
What does the code of practice say about recording ADRs?
- Drs MUST report (inform MHRA) all suspected ADRs to medicines and products with a black triangle in the BNFusing the yellow card scheme
- MUST inform MHRA about adverse incidents involving medical devices, incl. those caused by human error that put or have the potential to put the safety of pts and HCWs at risk
- should provide pts with information about how they can report suspected side effects to the MHRA
Why should we report ADRs?
important for pt safety
to identify ADRs not identified in clinical trials
to identify new ADRs
to compare drugs in the same therapeutic class
to identify ADRs in at risk groups
What reactions should be reported on a yellow card?
all suspected reactions for herbal medicines AND black triangle drugs
all serious suspected reactions for established drugs and vaccines
What does the black triangle mean?
a medicine that is undergoing additional monitoring
Give reasons as to why a drug may be undergoing additional monitoring
contains a new active substance
is a biological medicine eg a vaccine or a medicine derived from plasma
has been given conditional approval or only approved under certain circumstances
the company is collecting data on the drug
What is a serious reaction?
fatal life-threatening disabling or incapacitating results in hospitalisation prolongs hospitalisation
Who can report on a yellow card?
doctors dentists coroners pharmacists nurses midwives health visitors radiographers optometrists pts and carers and parents
What info should be included in a yellow card?
suspected drugs suspected reactions pt details reporter details additional useful info
