adverse drug reactions Flashcards
define adverse drug reactions ( ADR)
unwanted or harmful reactions following the administration of drugs or combination of drugs under normal conditions of use and is suspected to be related to the drug
define side effects
an unintended effect of a drug related to its pharmacological properties and can include unexpected benefits of treatment
describe what occurs depending on the severity of ADRs
- Can be mild e.g. nausea, drowsiness, itching rash
2.Can be severe e.g. respiratory depression, neutropenia, catastrophic haemorrhage, anaphylaxis
name some examples of adverse drug reactions
-Beta blockers
-Bradycardia and heart block are primary adverse effects
-Bronchospasm is a secondary pharmacological adverse effect
what is the wider impact of ADRs for patients
Reduced Quality of life
Poor compliance
Reduced confidence in clinicians and the healthcare system
Unnecessary investigations or treatments
what is the wider impact of ADRs for the NHS
Increased hospital admissions
Longer hospital stays
GP appointments
Inefficient use of medication
what is the Thompson classification of ADRs
A-ugmented
B-izarre
C-hronic/continuing
D-elayed
E-nd of use/withdrawal
F-ailure of treatment
G-enetic
describe type A reactions
(augmented pharmacological) – predictable, dose dependent, common, not life threatening
e.g- AKI with ACE inhibitors
Bradycardia with betablockers
Hypoglycaemia with gliclazide, insulin
Respiratory depression with opiates
Bleeding with anticoagulants
describe type B reactions
(bizarre or idiosyncratic) – not predictable and not dose dependent, can cause serious illness or mortality
e.g Anaphylaxis with penicillins
Tendon rupture with quinolone antibiotics
Steven Johnson Syndrome with IV vancomycin
describe type C reactions
(chronic) – osteoporosis and steroids, continue after the drug has been stopped
e.g Osteonecrosis of the jaw with bisphosphonates
Heart failure with pioglitazone
describe type D reactions
(delayed) – malignancies after immunosuppression, becomes apparent some time after stopping the drug
e.g Leucopenia with chemotherapy
describe type E reactions
(end of treatment) – occur after abrupt drug withdrawal
e.g Insomnia after stopping benzodiazepine
Rebound tachycardia after stopping beta-blocker
Nasal congestion after stopping xylometolazine nasal spray
describe type F reactions
(failure of therapy) – unexpected treatment failure, poor compliance with administration Instructions, failure of oral contraceptive pill in presence of enzyme inducer
e.g Failure of oral contraceptive pill due to St John’s Wort
Failure of DOAC due to enzyme inducer (eg carbamazepine)
Failure of bisphosphonate due to taking with food
describe type G reactions
( GENETIC)
drug causes irreversible damage to genome
e.g Phocomelia in children of women taking thalidomide
what is an alternative way to classify ADRs
DoTS
Dose-relatedness
Timing
Susceptibility
Describe D in DoTS
Hypersusceptibility: ADRs at subtherapeutic doses (eg anaphylaxis with penicillins)
Collateral effects (side effects): ADRs at therapeutic doses (eg hypokalaemia with loop diuretic)
Toxic effects: ADRs at subpratherapeutic doses (eg liver damage with paracetamol
describe T in DoTS
Time independent: ADRs which can develop during any time during treatment (often due to clinical changes in the patient)
describe S in DoTS
Susceptibility - certain groups/ populations may be more likely to delevlop ADRs
what groups are more likely in S in DoTS to develop reactions
Age (anticholinergics in elderly patients)
Gender (metoclopramide in females)
Disease states (eg diclofenac in CVD)
Physiological states (eg phenytoin in pregnancy)
how are ADRs identified?
Pre-clinical testing (computer models, cells and toxicity testing in animals)
Clinical trial data (pre-marketing evaluation)
Post marketing surveillance
Pharmacovigilance
causes for ADRs
Pharmaceutical variation
Receptor abnormality
Drug-drug interactions
when would you suspect an ADR?
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 restarted
name common ADRs
Confusion
Nausea
Balance problems
Diarrhoea
Constipation
Hypotension
what is the yellow card scheme
-The first ADR reporting scheme
-Collects spontaneous reports
-Acts as an ‘early warning system’ for identification of previously unrecognised reactions
-Provides information, about factors which predispose patients ADRs
-Continual safety monitoring of a product throughout its life span as a therapeutic agent
