Pharmacogynetics and ADR's Flashcards
Define an adverse drug reaction
An adverse drug event occurs “while a person is taking a drug , but is not necessarily due to the drug”
State and describe the two types of adverse drug reactions [ADR’s]/
Type A
Predictable
Dose related
Often an exaggeration of the therapeutic effects
E.g. a patient taking an antihypertensive drug may feel dizzy or light headed
Type B Unpredictable May not be dose related Includes allergic reactions E.g.- skin rashes, jaundice and anaemia
Adverse drug reactions are classified into six types (with mnemonics): dose-related (Augmented), non-dose-related (Bizarre), dose-related and time-related (Chronic), time-related (Delayed)
Type B ADR is classified as a drug allergy. How does this happen in the body? and what are the reactions
Occur when the body forms antibodies to a particular drug
An allergic reaction occurs after second or subsequent exposure (may be delayed)
Reactions may be: Anaphylactic Tissue specific Immune complex- mediated Cell mediated
Examples of drugs that may fall under type b
Penicillins, metronidazole, anticonvulsants, antibiotics, local anaesthetic creams
Pharmacovigilance meaning
The science and activities relating to the detection, assessment, understanding and prevention of adverse effects or any other drug-related problem
What is the NZ centre for adverse reactions monitoring
CARM - National monitoring centre for ADR’s.
Risk factor for ADR’s
Age (elderly) Gender- women Concurrent disease Genetics History of past reactions Pharmaceutics (chemical characteristics) Route of administration Dose duration and frequency
pharmacokinetic interaction. Distribution
Drugs may compete for protein binding sites. Name an example
Warfarin is 99% protein bound and so only 1% is free to exert an effect. If a second drug displaces any of the Warfarin bound to protein the amount of free Warfarin is significantly increased
Enzyme induction - When a drug is present in the body for prolonged periods the amount of metabolising enzyme can increase and thus speed up metabolism of that drug.
This can decrease the concentration of active drug meaning the patient may require an increase in drug dosage
E.g. Rifampicin, Morphine
Name examples of enzyme inducers
Other substances can act as enzyme inducers also E.g.- alcohol, tobacco smoke.
If a drug or food inhibits a metabolising enzyme it is known as an
enzyme inhibitor.
Substances that cause enzyme inhibition may lead to
the accumulation of drugs in the body leading to toxicity
CYP3A4 metabolises up to __% of all CYP450 metabolised drugs
50%
Excretion
Drugs may compete for the same transport system
name an example
Probenecid with IV penicillin- inhibits tubular secretion of the penicillin therefore prolonging its action
Several drugs are known to interact with foods
Tetracycline and milk products
Warfarin and Vitamin K containing foods
Grapefruit Juice
define Pharmacogenetics
The effect of genetics on drug action and elimination
pharmacogenetics - Human populations can be divided into two groups extensive and poor metabolisers
name an example of pharmacogenetics
E.g 6-10% of the Caucasian population lack the enzyme to metabolise codeine (
This drug only has an effect on tumours in people who’s tumours display a specific genetic defect
E.g Trastuzumab (Herceptin).
Pharmacogenomics meaning
Area of study looking at individual variation in drug response due to genetic factors
A patient had a cardiac arrest when he was inadvertently given an overdose of potassium supplement. This incident can be defined as a/an:
This is an example of an adverse drug event (ADE). ADE includes under- or over-medication resulting from errors in drug ordering, dispensing or administration.
Tardive dyskinesia as a result of long-term neuroleptic use can by categorised as which type of adverse drug reaction?
Type C (Continuous) ADRs occur because of long-term drug use.
There are more adverse drug reactions among:
ADRs among the elderly are more common because they are more likely to be taking multiple medications.
Certain genetic factors predispose individuals to ADRs:
T/F
True - This has been known since the late 1950s; the move towards the era of pharmacogenetics will enable medication prescriptions to be tailored to individual genotypes.
Drug allergy is a common adverse drug reaction:
T/F
F - It usually occurs in a small number of individuals taking the drug.
Individuals with a history of atopic disease are more likely to experience adverse drug reactions: T/F
T - There is a positive association between atopic disease (e.g. asthma, hay fever and eczema) and allergic drug reactions.
An adverse drug reaction (ADR) is defined as
noxious, unintended drug response
An anaphylactic reaction to a small dose of penicillin can by categorised as which type of adverse drug reaction:
Type B
The development of cervical cancer in female offspring of mothers who used to take diethylstilboestrol (DES) during pregnancy can by categorised as which type of adverse drug reactions:
Type D (Delayed) ADRs are characterised by the appearance of delayed effects.
Break down the four types of ADR’s.
Characteristics of type A (Augmented) ADRs include:
i) predictability; ii) dose response relationship; iii) common occurrence; iv) high morbidity and low mortality.
Characteristics of type B (Bizarre) ADRs include: i) unpredictability; ii) no dose response relationship; iii) uncommon occurrence; iv) high morbidity and high mortality.
Type C (Continuous) ADRs occur because of long-term drug use.
Type D (Delayed) ADRs are characterised by the appearance of delayed effects.
The physician has written admission orders, and the nurse is transcribing them. The nurse is having difficulty transcribing one order because of the physician’s handwriting. Which of the following is the best action to take at this time? The nurse should:
do not transcribe a prescription as this is not within the RN’s scope of practice
Many ADR’s are ____ related
Dose
