adverse drug reactions

Question 1

what is an adverse drug reaction defined as?

Answer 1

any response to a drug which is noxious, unintended and occur at doses used in man for prophylaxis, diagnosis or treatment

Question 2

what are the 3 classifications for onset of adverse drug reactions?

Answer 2

acute - within 60 minutes
sub-acute - 1 to 24 hours
latent - >2days

Question 3

what are the three classifications for the severity of adverse drug reactions?

Answer 3

mild
moderate
severe

Question 4

what are the classifications of adverse drug reactions?

Answer 4

type A - augmented
type B - bizarre
type C - chronic
type D - delayed
type E  - end of treatment
type F - failure of treatment

Question 5

what are some predisposing factors to ADRs?

Answer 5

multiple drug therapy
age - more common in the elderly and neonates
sex- more common in women
renal and hepatic impairment
race and genetic polymorphisms

Question 6

what are some features of type A ADRs?

Answer 6

normal but augmented response to a drug
entirely predictable
due to excess pharmacological action (e.g. bradycardia with beta blockers)
they are dose dependent
resolve when the drug is reduced or stopped

Question 7

what are some reasons that a type A ADR would occur?

Answer 7

too high a dose
pharmaceutical variation
pharmacokinetic variation
pharmacodynamic variation
last 2 commonly occur as a result of disease

Question 8

what factors can affect absorption of a drug?

Answer 8

dose
formulation
GI motility
first pass metabolism

Question 9

when is liver disease particularly important when considering what drug therapy to use?

Answer 9

when drugs have a narrow therapeutic index

Question 10

why is it important to determine whether or not a patient is a slow metaboliser?

Answer 10

a number of drugs are metabolised via acetylation - slow metabolisers are more prone to drug toxicity

Question 11

what is an example of a pharmacogenetic ADR?

Answer 11

peripheral neuropathy with isoniazid

Question 12

what are the consequences of cardiac failure with regard to ADRs?

Answer 12

reduced drug absorption from the gut due to oedema
poor renal perfusion and decreased GFR
hepatic congestion

Question 13

what are the features of an immunological type B ADR?

Answer 13

no relation to the pharmacological action of the drug
delay between exposure and ADR
no dose response curve
can manifest as rash, asthma, serum sickness

Question 14

what are some features of type C ADRs?

Answer 14

related to the duration of treatment as well as the dose
does not occur with a single dose
semi predictable

Question 15

what are features of type D ADRs?

Answer 15

can occur sometime after treatment in both the children of patients and the patients themselves

Question 16

what are some features of type E ADRs?

Answer 16

adverse effects occur when a drug treatment is stopped especially suddenly (rebound phenomena)

Question 17

what are some example of drugs that would cause a type E reaction when suddenly stopped?

Answer 17

alcohol
benzodiazepines
beta blockers
corticosteroids

Question 18

what are the steps in diagnosing an ADR?

Answer 18

differential diagnosis
patients past and current medication history
assess time of onset and dose relationship
laboratory investigations (plasma conc. management and allergy tests)