Lecture 10 Flashcards
Adverse drug reactions and medication errors (63 cards)
1
Q
What is an adverse drug reaction?
A
unintended and undesired response from drugs
- 7.5% of hospital admissions in CAN attributed to ADRs
2
Q
What counts as an ADRs?
A
- side effects
- drug toxicity
- allergic reaction
- idiosyncratic reaction
- carcinogenic effects
- mutagenic effects
- teratogenic effects
3
Q
What are side effects?
A
- secondary to the main therapeutic effect due to poor drug specificity or selectivity & often occur at normal therapeutic doses & are unavoidable
4
Q
Example of a side effect (antihistamines)
A
- act by blocking H1 histamine receptors to prevent symptoms of allergy
- antihistamines can bind to either histamine receptors or other receptors in the brain which lead to side effects
5
Q
What is drug toxicity?
A
- any severe adverse event
- often overdose where patients unintentionally or intentionally take too much medication
- often extensions of the therapeutic effect
6
Q
What is an allergic reaction?
A
- mediated by the immune system which requires prior sensitization (patient exposed to allergen)
- mast cells release chemical mediators such as histamine
7
Q
Does dosage size affect an allergic reaction?
A
- no, they are independent
8
Q
What % of all ADRs are drug related?
A
10%
9
Q
What are the most common drug classes to cause allergic reactions?
A
- penicillins
- sulfoamides
- nonsteroidal anti-inflammatory drugs
10
Q
Where on the body are allergic reactions most common? least common?
A
- most: abdomen
- least: head
11
Q
What are idiosyncratic reactions?
A
they are reactions that occur rarely and predictably in the population
- genetic polymorphisms account for majority of IRs
12
Q
What kind of genetic polymorphisms cause the majority of IRs?
A
- ones in drug metabolizing enzymes and drug transporters
13
Q
Which drugs can currently have blood tests done to determine if they will cause an IR?
A
- warfarin and 6-mercaptopurine (metabolized by CYP2C9 and TPMT respectively)
14
Q
Example of polymorphisms: CYP2C9
A
- approx 15% of caucasians have a polymorphism that decreases metabolism
15
Q
Example of polymorphisms: CYP2D6
A
- 10% of cauc’s and afric. americans are poor metabolizers
- patients do not experience pain relief when they take codeine which is metabolized by this to morphine
16
Q
Example of polymorphisms: Thiopurine methyltransferase (TPMT)
A
- 10% have decreased activity and 0.3% have no activity
- thiopurine drugs can result in life threatening bone marrow suppression
17
Q
Example of polymorphisms: OAP1B1
A
- uptake drug transporter in the liver
- 15% of asian and cauc’s have this
- leads to increase in plasma drug concentrations
- can cause myopathy (muscle toxicity) in patients taking statin drugs
18
Q
Example of polymorphisms: Glucose 6-phosphate dehydrogenase deficiency (G6PDH)
A
- important in red blood cell metabolism
- common in ppl of african/middle eastern descent
- may have red blood cell hemolysis following treatment with certain analgesics (i.e aspirin) or anti-malarial drugs
19
Q
What are carcinogenic effects?
A
- ability of a drug to cause cancer (relatively few drugs are)
- difficult to determine bc takes years after initial dose to appear
20
Q
Example of carcinogenic drug
A
- diethylstilnestrol (DES) used to be prescribed to prevent spontaneous abortion in high risk pregnancies
- later determined it caused female offspring to develop vaginal/uterine cancer
21
Q
What are mutagenic Effects?
A
- drugs that are able to change DNA
- often also carcinogenic or teratogenic
22
Q
How are drugs tested for their potential as mutagens?
A
- Ames test: evaluates the ability of the drug to cause a mutation in specialized strains of bacteria
23
Q
What are teratogenic effects?
A
- produce birth defects or impair fertility
- can be physical malformations or behavioural and metabolic defects
- less than 1% of birth defects caused by drugs
24
Q
How does sensitivity to teratogens change during fetal development?
A
- gross malformations usually form when exposed during 1st trimester
- 2nd & 3rd tri: disrupts function as opposed to anatomy
- transfer of drugs across placenta greatest in 3rd tri bc SA is the largest, increased circulation and thin placental-fetal barrier
25
Area with highest sensitivity throughout pregnancy
- CNS
26
areas with highest sensitivity in 1st trimester
- heart
- upper & lower limbs
- lip
- ears
- eyes
- teeth
- palate
- genitalia
27
What are the pregnancy risk categories?
-A, B, C, D, X
28
Category A
- no risk to fetus in 1st trimester (human studies)
| - no evidence of harm later in pregnancy
29
Category B
- animal studies failed to show harm to fetus but no human studies
OR
- animal studies show adverse effects but human studies do not
30
Category C
- animal studies show hard to fetus but no human studies
| - potential benefits outweigh potential risk
31
Category D
- clear evidence of risk to fetus in human studies
| - potential benefits outweigh the risks
32
Category X
- animal and human studies show risk
- risks outweigh benefits
- never to be used on pregnant women
33
Where does the most common organ specific toxicity occur?
- liver and heart
34
What is heptatoxicity?
-some drugs metabolized in liver to toxic metabolites which can cause injury
35
What the are signs of liver toxicity?
- jaundice (yellow skin)
- dark urine
- light-coloured stool
- nausea and vomiting
36
What is measures in liver function tests?
- aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels in blood
37
What is QT interval prolongation?
major risk factor for the development of torsades de pointes, a life threatening form of ventricular arrhythmia
38
P-wave
normal atrial depolarization
39
QRS
rapid depolarization of the left and right ventricles
40
T-wave
repolarizarion of ventricles
41
QT interval
represents the time required for the ventricles to repolarize
42
How many drugs are known to prolong QT interval?
- more than 100
43
In what kind of patients should QT prolonging drugs we used with caution in?
- predisposed to arrhythmias (elderly)
- bradycardia (slowed heart beat)
- heart failure
- low potassium
- congenital QT prolongation
44
Which gender is more at risk with QT interval drugs?
- women bc their normal QT interval is longer
45
What are the consequences of rapid withdrawal of opiates?
- anorexia, irritability, nauseas, vomiting, weakness, muscle spasms
46
What are the consequences of rapid withdrawal of Benzodiazepines?
- anxiety, insomnia, sweating, tremors, panic, delirium, paranoia, convulsions
47
What are the consequences of rapid withdrawal of beta blockers?
- rebound hypertension, chest pain, myocardial infarction, arrhythmia
48
What are medication errors caused by a health care professional called?
- iatrogenic errors
49
What are the 5 main categories of medication errors?
1. prescribing
2. dispensing
3. administration
4. patient education
5. patient
50
Medication errors with prescribing
- health care prof prescribes wrong drug, dose or route
51
Medication errors with dispensing
- prescription correct but pharmacist dispenses wrong drug
52
Medication errors with administration
- HCP administers the incorrect dose or drug (patient can also make this error)
53
Medication errors with patient education
- illiteracy or language barriers cause patient to fuck up instructions
54
Medication errors with Patients
- patient understands the instructions but doesnt follow them (misses dose, takes more meds than prescribed)
55
Medication errors in drug naming
- likely to occur when drug names look/sound the same
| - represents ~15% of all medication errors
56
What are some common drug naming errors?
plendil --> pletal
nicoderm --> nitroderm
flomax --> volmax
dioval --> diovan
57
Errors and abbreviations
- dangerous source of erros
| - institute for safe medication practices made list of shit to avoid
58
what is IU (international units) misinterpreted as?
IV or 10
59
What is q.d (everyday) misinterpreted as?
qid
60
what is q.o.d (every other day) misinterpreted as?
q.d or qid
61
What can trailing zeros after decimal point be misinterpreted as (ex 1.0 mg)
10 mg
62
What can MgSO4 be misinterpreted as?
morphine sulfate
63
What can Ms, or MSO4 be misinterpreted as?
magnesium sulfate
