Adverse drug reactions Flashcards
What is an adverse drug reaction?
A response to a drug that s noxious and unintended and which occurs at doses usually used in man for the prophylaxis, diagnosis, or therapy of disease, or for the modification of physiological function.
What amount of ADR’s result from medication errors? (eg errors inprescribing, dispensing, administering etc)
Not very many - only about 25%
What is the difference between an allergy and a side effect?
An allergy is a type of adverse drug reaction that is mediated by an immune response (eg, rash, hives)
A side effect is an expected and known effect of a drug that is not its therapeutic outcome (ie an adverse drug reaction)
ADR’s can be classified in one of two ways; ABC’s or DoTs. What do these two acronims mean?
Type A = augmented
Extension of normal intended effect eg anticholinergic effects with tricyclic antidepressants.
Type B = Bizarre
Rare and unpredictable drug allergy eg penicillin
Type C = Chronic effects
Associated with long term use eg NSAID’s can damage stomach if taken for too long
Type D = Delayed effect
Type E = end of treatment
eg stopping antidepressants
Type F = Failure of treatment
DoTs
D= Dose
Supratherapeutic dose, normal dose, subtherapeutic dose in hypersensitive patient
T = Timing
Time independent reaction or time dependent reactions (rapid, delayed, first dose, late etc)
S = susceptibility
Hypersensitvity due to genetics, age, sex,, phsyiological variation, disease etc
How can drug allergies be classified?
Immediate - occur within one hour (anaphylactic)
Mediated by IgE and mast cells
Delayed - occur after one hour, mostly after 6
Cytotoxic, immune complex or T cell mediated
What kind of effect do ADR’s have on the health system in NZ?
12.9% of public hospital admissions were associated with ADR’s and HALF of these NZ events were preventable.
What are three of the most common drugs that cause ADR’s?
Anticoagulants, opioids, and insulin
What are some risk factors that make some people aat higher risk of an ADR?
- children
- comorbidities (older patients)
- imparied hepatic or renal function
- women
- race and genetic polymorphisms within ethnicities.
How can we prevent ADR’s? Two of the main strategies are computerised physician entry and medication reconciliation. Describe these factors
Computerised entry:
Doctors order medication for a patient online. This could help their writing be legible so there isnt any medication errors when dispensing etc, it could pop up with alerts about the patients allergies and possible interactions with their other drugs or substances, it could have a calculator to enter in patient characteristics to get a dosage calculation.
Medication reconciliation:
Verification -reviewing the patients medication, clarification - ensuring the medications and doses are appropriate, reconciliation - making any appropriate changes, identifying any discrepancies between medication ordered for patients and those in the list
What is pharmacovigilence?
Also called post marketing surveillence.
After a drug has been developed and released onto the market it is important to identify, report and respond to risk benefit issues arising with marketed medicines.
What to do is you suspect someone has had an ADR
Always consider the possibility that a drug may be associated with worsening of a patients medical condition or with a new medical problem.
Rule out other explanation and investigate the known effects of the drug.
If you do suspect it is an ADR then withdraw the medicine, record susepcted ADR in drug chart, inform the patient and doctor, complete a CARM (centre for adverse drug reactions) form.
What are some strategies for avoiding ADR’s?
- do not give a drug unless absolutely required
- try to use common medicines not new ones that you dont the effects of
- give clear instructions on how to take them
- check for other medications including herbal teas or supplments that the patient is already taking
- check for previous reactions or allergies
- if at high risk, start on small dose
- warn the patient of adverse drug effects and what to look out for
