Adverse drug reactions Flashcards
ABCDE classification of ADRs; Factors that contribute to ADRs; High risk pt groups; Severity classification of ADRs; Incidence classification of ADRs; Identifying ADRs; Common ADRs; Clinical trials; Reporting ADRs; Effect of interactions; Mechanism of drug interactions; Food and drink interactions
Definition of an ADR
?dose, given for what?
Toxic, unintended response of body to drug when given at a normal dose for treatment/prophylaxis
4 features of ADRs
always … and …, detrimental to … cause complications to …
Always harmful
Always impact pts recovery/wellbeing
Detrimental to patients trust in prescriber and drug
Cause complications to care/finances
ADRs can be useful true or false?
True
Is an overdose an ADR?
No
Definition of an adverse drug event
Group term for the errors made when prescribing or dispensing a drug
What are the 3 types of ADR classification?
ABCDE
Severity
Incidence
What does the ABCDE of ADR classification stand for?
Augmented Bizzare Chronic Delayed End of dose
Definition of a augmented ADR?
Excessive reaction to a drug
What are 3 features of an augmented ADR?
Frequency, ?morbidity ?mortality, related to …, can they be predicted?
Common- high morbidity, low mortality
Dose related
Predictable yes
Definition of a bizzare ADR?
unpredictable reaction to a drug
What are 3 features of a bizzare ADR?
severity, are they dose related, effect which group why
Serious
Not related to dose
Likely to effect minority groups as they are not included in clinical trials
Definition of chronic ADR
Induced over a long time, body adapting to drug
Definition of a delayed ADR
Develops after a period of time having had the drug
Definition of end of dose ADR
Withdrawl reaction when drug is stopped
Where can the incidence of ADRs for a drug be found?
Under summary of produce characteristics
What unit are incidence ADRs given in and what for patients are they better being given as?
%
Better given as frequency
5 classifications of incidence ADRs
Very common Common Uncommon Rare Very rare
What is the % and frequency (fraction) of a very common ADR?
> 10%
>1/10
What is the range of % and frequency (fractions) of a common ADR?
1-10%
1/100 - 1/10
What is the range of % and frequency (fractions) of a uncommon ADR?
01-1%
1/1000 - 1/100
What is the range of % and frequency (fractions) of a rare ADR?
0.01-0.1%
1/10000 - 1/1000
What is the % and frequency (fraction) of a very rare ADR?
<0.01
1/10000
4 categories of ADR severity
Mild
Moderate
Severe
Life threatening
Definition of a mild ADR
May not be noticed by pt
Definition of a moderate ADR
Requires correcting but doesnt require admission to hospital
Definition of a severe ADR
Damage to patients organs, requires hospital admission
7 factors that contribute to pts risk of ADR
Age Sex Ethnicity Comorbidities Allergies Polypharmacy Narrow therapeutic index
7 high risk pt groups for ADRs
Elderly Children Female Heart arrythmia HIV Abnormal metabolism Allergies
6 reasons why elderly are at increased risk of ADR
Organ deterioration Low homeostatic reserve, less ability to compensate Cardiac/CNS drugs effect at lower dose New drug may cause AKI Multiple comorbidities Polypharmacy
4 reasons why children are at increased risk of ADRs
Different metabolism/excretion of drugs to adults
Different pharmodynamics
Children excluded from clinical trials
Water and fat distribution changes quickly altering drug distribution
2 reasons why ADRs more common in females than males
?better reporting
Difference in hormonal/immune systems
What area of the body is more likely to have a reaction to drugs in HIV patients?
Skin
If patient experiences suspected ADR should another drug be added, or ?
Drug causing ADR should be changed
Acronym for identifying ADRs, what does each letter stand for and mean?
TRIP
Time - of ADR after drug administered
Recovery - ADR stop after not taking drug
Independent - test to objectively monitor ADR e.g. BP
Predictable - ADR understandable from drug’s method of action
5 common drug interactions and their resulting ADRs
NSAIDs + corticosteroids = dyspepsia Laxatives + abx + cytoxics = diarrhoea ACE inhibitors = dry cough Opioids + tricyclic antidepressants + iron = constipation Opioids + cytotoxics + SSRIs = Nausea
5 common food/drink interactions with drug/their effect
Grapefruit juice - enzyme inhibitor Cranberry juice + warfarin Milk/dairy products = chelation Alcohol + antidepressants = additive St Johns Wort + oral contraceptives = enzyme inducer
What does chelation mean?
Formation of insoluble compounds by agents converting metal ions into inert versions of drug
6 ways to reduce ADRs
Take pt history - predisposing factors, high risk group
Current/past drug history
Medication reviews
Regular monitoring of known ADRs - drugs with narrow therapeutic index
Pt aware of what to do when ADR occurs
Prescription of lower risk drug
Definition of pharmacovigillance
Monitoring of a drugs effect after on population being introduced to see its effect
Definition of a drug interaction
presence of what on what, changes what
Occur when effect of a drug or food changes with presence of another drug, chemical or food
How can you identify a drug interaction in the BNF?
Will have a black dot next to it
Or be in bold text with a pink background
3 outcomes of drug interaction
work any more?, effect
Ineffective
Increase in effect
Beneficial harmful effect
Definition of a drug with a narrow therapeutic window
Difference between therapeutic and toxic dose of drug is very small
What should be done when a patient is on a drug with a narrow therapeutic window and to ensure what?
Monitor plasma concentration of drug to ensure concentration remains within therapeutic range
Name 2 types of drug interaction effect
Additive
Antagonistic
Define a additive interaction effect
Drug interaction increases or adds to drugs effect
Define a antagonistic drug interaction effect
Drug counteracts the action of the other, meaning desired therapeutic effect doesnt occur
Name 2 mechanisms of drug interaction
Pharmodynamically
Pharmokinetically
What feature of a drug to the one being given may result in a pharmodynamic interaction?
Drug with similar antagonist effect
What 3 things might cause one drug interact to effect the absorption of another drug?
Dose of drug
Alteration of GIT motility/pH
Chelation
How might a drug interact with another to effect its distribution?
(displace where, why cause ADR)
Displacement of protein bound drug- leaving unbound drug bioactive causing ADR/toxicity
Lower albumin concentration - same reason as above
How in general terms might a drug interact with another to effect metabolism?
Increase or decrease the rate of drug break down
What would a drug do to increase the metabolism of another?
Induce enzymes
What is the effect of a drug enzyme inducer on drug concentration?
Decrease plasma concentration of drug
What would a drug do to decrease the metabolism of another?
Inhibit enzymes
What is the effect of a drug enzyme inhibitor on drug concentration?
Increase in plasma concentration of drug
Would drug dose need to be increased or decreased when taken with a enzyme inducer to have same therapeutic effect?
Increased
Would drug dose need to be increased or decreased when taken with an enzyme inhibitor to have same therapeutic effect?
Decreased
How might one drug interact to effect the excretion of another when they are both excreted renally? Ad what effect on drug plasma conc would this have?
Compete to be removed
Increase drug plasma concentration
Clinical trials only identify common ADRs true or false?
True
What is the usual sample size involved in a clinical trial?
1500
What 2 incidences of ADRs wont have occurred in a clinical trial?
Uncommon and rare
Is the duration of a clinical trial short or long?
Short
True or false, clinical trials involve minority populations?
False
What system and organisation is in place to report ADRs?
Yellow card scheme to MHRA
In well established drugs which ADRs should be reported?
Serious, medically significant ADRs with harmful reactions
What should be reported as an ADR?
which drugs, just drugs?, smoking
Ineffective drugs
Medical devices
Conterfeit drugs
Nicotine devices
What group term should all ADRs be reported for?
Minority groups e.g. elderly, children etc
What symbol shows that a drug is new and under increased monitoring?
Upside down black triangle
Where can you find out if a drug is new and under increased monitoring?
(2 places_
On summary of medical product characteristics
On patient information leaflet
In a new drug identified with a upside down triangle should all ADRs be reported, Yes or no?
Yes
