Adverse drug reactions Flashcards
Define ADRs
Unwanted or harmful reactions following administration of a drug or combination of drugs under normal conditions of use and is suspected to be related to the drug
Define side effect
Unintended effect of a drug related to its pharmacological properties and can include unexpected benefits of treatment
How common are ADRs
One in 20 hospital admissions (5% of all admissions)
How common are ADRs in hospital inpatients
10-20%
5th most common death
Why are ADRs so important to avoid
- Affects QOL
- Increase cost of patient care
- Loss of confidence in doctors
- May mimic disease
Adverse drug reactions to Beta blockers
- Bradycardia and heart block - primary
2. Bronchospasms - secondary
What are type A drug reactions
AUGMENTED PHARMACOLOGICAL - Predictable, dose dependant and common
What are type B drug reactions
(BIZARRE) - not predictable or dose depentant
What are type C drug reactions
CHRONIC - Osteoporosis and steoirds
What are type D adverse drug reactions
DELAYED - Malignancies after immunosuppression
What are type E adverse drug reactions
END OF TREATMENT - occur after abrupt drug withdrawal
What are type F drug reactions
FAILURE of therapy - Failure of OCP in presence of an enzyme inducer
What does DoTS stand for
Dose relatedness
Timing of delivery (fast or slow infusion etc)
Patient susceptibility
What are patient risk factors for ADRs
Patient
- Gender
- Elderly
- Neonates
- Polypharmacy
- Genetic predisposition
- Hypersensitivity
- Hepatic
- Adherence problems
What are Drug risk factors for ADRs
Steep dose-response curve
Low therapeutic index
Prescriber risks
What drug causes type A adverse drug reactions in the lungs
- Propranolol
Why does propranolol cause bronchospasm (secondary)
Blocks beta-2 receptors
What are problems with Type B adverse drug reactions
Not readily reversed
Less common
Life-threatenening
Allergies fall under this
What is an idiosyncrasy
Inherent abnormal response to a drug
Genetic abnormality
Abnormal receptor activity
How are enzyme-associated idiosyncrasy obtained
Deficiency obtained from X-linked
Examples of enzyme deficient idiosyncrasy
Glucose-6-phosphate dehydrogenase and primaquine
What can G6PD and Primaquine deficiency lead to
Haemolysis and haemolytic anaemia
What factor can cause receptor abnormality idiosyncrasy
Malignant hyperaemia caused by general anaesthetics causes sudden huge rise in calcium concentration
- Increase in muscle contraction
- Increase in metabolic activity
- Rise in body temperature
How does vaccination cause hypersensitivity
- First dose acts as antigen
- Antibody produced
- Second dose causes antibody-antigen reaction
Four types of hypersensitivity reactions
Type A - Allergy and anaphylactic
Type B - AntiBody
Type C - immune Complex reaction
Type D - Delayed Hypersensitivity
Example of Type A hypersensitivity
Penicillin allergy
Example of Type B hypersensitivity
Haemolytic anaemia
Example of Type C hypersensitivity
Rheumatoid arthritis
Example of Type D hypersensitivity
Contact Dermatitis
Examples off type D adverse drug reaction s
Teratogenesis from thalidomide
Carcinogenesis from cyclophosphamide causing bladder cancer
Examples of Type E adverse reactions
Glucocorticoid abruptly withdrawn leads to adrenocortical insufficiency
Withdrawal seizures when anti-convulsants are stopped
4 signs we should expect an ADR
- Symptoms soon after new drug is started
- Symptoms after a dosage increase
- Symptoms disappear when drug is stopped
- Symptoms reappear when drug is restarted
Most common drug to have ADRs
NSAIDS
Antibiotics
Common ADRs
- Confusino
- Nausea
- Diarrhea
- Constipation
- Hypotension
How can ADR’s be avoided
- Prevent drug interactions
- Inappropriate medication
- Unnecessary medication
Role of MHRA
Responsible for approving medicines and devices for use
Watch over medicine and take action s to protect public promptly if there is a problem
What is the yellow card scheme
Introduced in 1964
- Collects reports on ADRs
- Collects suspected adverse drug reactions
Is the yellow card scheme compulsory
No
Why is the yellow card scheme important
Acts as an early warning system for identification for previously unrecognised reactions
Provides information about factors which predispose patients to ADRs
Advantages of yellow card scheme
- One of the most effective method of identifying rare adverse reactions
- Work rapidly
- Applied to all drugs throughout marketing life
- Cheap
Disadvantages of a yellow card
- Can’t provide evidence as true number of cases is underestimated and total number of patients exposed is unknown
- Relies on ADR being recognised
- Media interest in drugs will stimulate more ADR reports
- Reporting high for new drugs and falls off over time
- NOT ALL ADRs are reported
Why are ADRs under-reported (10% of all cases)
- Ignorance - Not sure how to report
- Diffidence - May appear foolish for reporting
- Fear - Expose myself to legal liability
- Lethargy - too busy
- Guilt - Reluctant to admit i caused it
- Ambition - Rather collect cases and publish them myself
- Complacency - Only safe drugs are marketed
Why do we report ADRs
Important for patient safety
- Identify ADRs not identified in clinical trials
- Identify new ADRs ASAP
- Compre drugs at same therapeutic class
- Identify ADRs in at risk groups
What is reported on a yellow card
All suspected reactions for herbal medicines and black triangle drugs
All serious suspected reactions for established drugs, vaccines and interactions
Define black triangle drugs
Medicine undergoing additional monitoring
When is the term black triangle given
- Contains new active substance
- Biological medicine (vaccines)
- Only approved under certain circumstances
What is a serious reactions
- Fatal
- Life-threatening
- Disabling
- Hospitalisation
- Prolongs hospitalisation
Who can report on a yellow card
- Doctors
- Dentists
- Coroners
- Pharmacists
- Nurses
- Patients
What four important pieces of information must go on a yellow card report
- Suspected drugs
- Suspect reactions
- Patient details
- Reporter details
