Principles of drug use

Question 1

What are the 3 factors contributing to adverse drug reactions? (DoTS)

Answer 1

Dose
Time-course
Susceptibility

Question 2

What are the 3 types of reactions associated with ADRs? Above, below and within therapeutic range?

Answer 2

Above = toxic reaction
Within = collateral reaction
Below = hypersusceptibility

Question 3

What are the 6 types of reactions associated with time-course related ADRs?

Answer 3

First dose reactions
Early reactions
Intermediate reactions
Late reactions
Withdrawal reactions
Delayed reactions

Question 4

What is the definition of drug clearance? what is it measured in? equation?

Answer 4

‘The volume of plasma cleared of drug per unit time’
mL per minute
CL= rate of elimination from body/plasma drug conc

Question 5

What is first order kinetics of drug elimination?

Answer 5

Drug concentration decreases exponentially over time. Relationship between natural logarithm of drug concentration and time is linear

Question 6

How does ageing bring about changes in pharmacodynamics?

Answer 6

Receptor sensitivity
Receptor number
Hormone levels
Medicines affecting CNS and CVS are freq altered

Question 7

What are some pitfalls in prescribing for elderly?

Answer 7

Concordance/compliance issues (do they want to take it?/remember?)
Cognitive/visual
OTC
Prescribing cascade

Question 8

What are some strategies to improve condordance? (SEM)

Answer 8

Simplify
Educate
Monitor

Question 9

What framework sets standards for medication review in the elderly population?

Answer 9

National Service framework

Question 10

What is an example of a toxic reaction? how would you treat/prevent it? (above therapeutic range)

Answer 10

Bleeding following too high dose of anticoagulant
Treat - reducing dose
Prevent - minimal effective dose

Question 11

What is an example of a collateral reaction? how would you treat/prevent it? (within therapeutic range)

Answer 11

Drowsiness with antidepressant

may not be reduced even by reducing dose

Question 12

What is an example of a hypersusceptibility reaction? how would you treat/prevent it? (below therapeutic range)

Answer 12

Penicillin allergy
Avoid by foreknowledge of patient susceptibility
Permanent avoidance of drug

Question 13

What are some examples of:
First dose reactions (FDR)
Early reactions (ER)
Intermediate reactions (IR)
Late Reactions (LR)
Withdrawal reactions (WR)
Delayed reactions (DR)

Answer 13

FDR - Hypotension after 1st dose of ACEi
ER - Nitrate induced headache
IR - Thromboembolism due to antipsychotics
WR - SSRI antidepressant discontinuation
DR - severe WC loss following chemo drug use

Question 14

What should we assume for older patients in terms of kidney function?

Answer 14

At least mild renal impairment