20 - ADRs

Question 1

List some reasons why ADRs occur (5 total)

Answer 1

• Can interact w/ other drugs
• Not all is known about safety of drug when marketed
• Misuse
• Patient factors
• Pharmaceutical factors

Question 2

What makes someone susceptible to ADRs? (6 total)

Answer 2

• Polypharmacy
• Age (very young or very old)
• Gender
• Concurrent disease
• Genetics
• Allergy

Question 3

1) Do natural health produces count as causing ADRs?
2) Does using at higher doses of a drug then normal count as an ADR?

Answer 3

1) Yes
2) No

Question 4

Type A ADRs?

Answer 4

Augmented
- Predictable from pharmacology of medicine
- Dose-related

Question 5

Type B ADRs?

Answer 5

Bizarre
- Not predictable from pharmacology
- Not dose related
- Less common than type A

Question 6

Type C ADRs?

Answer 6

Chronic
- Following prolonged use

Question 7

Type D ADRs?

Answer 7

Delayed
- Occurs remote in drug user or in offspring of user

Question 8

Type E ADRs?

Answer 8

End of treatment
- When withdrawing treatment

Question 9

Type F ADRs?

Answer 9

Failure
- Lack of efficacy of drug

Question 10

Type G ADRs?

Answer 10

Genetic
- Genetic susceptibility

Question 11

Problems with the current classification for ADRs?

Answer 11

• All ADRs are dose-related to some degree
• Genetic susceptibility is important in all types (more or less)
• Overlap in categories e.g. type A + type C/D/E

Question 12

1) Drugs can interact w/…
2) Drug interactions can either be…

Answer 12

1) Drug-drug/NHP/food/drink/device/environmental agent
2) Pharmacokinetic (affects it’s ADME) or pharmacodynamic.

Question 13

Best place to check for drug interactions?
- What about for UoA?

Answer 13

NZ formulary
- Stockley’s Drug Interactions is a reference for a bunch of drug interactions.

Question 14

How can drug interactions affect absorption?

Answer 14

Since most drugs given orally, have to go through GI tract.
Interactions can affect:
- Rate of drug absorption
- Amount of drug absorbed
This can be due to:
- pH changes
- Absorption, chelation, and other complex stuff e.g. antacids absorb onto other drugs.
- Motility changes
- Induction/inhibitoon of drug transporter proteins.

Question 15

How can drug interactions affect distribution?

Answer 15

Plasma-protein binding can be competed against and displace each other.
In practice, few clinically relevant interactions occur.

Question 16

How can drug interactions affect metabolism?

Answer 16

• Most drugs chemically altered to less lipid-soluble, usually inactive drugs (unless prodrug).
• Liver metabolises drugs w/ enzymes
• Metabolism of a drug can be inhibited/reduced by another drug.

Question 17

How can drug interactions affect elimination?

Answer 17

Due to:
- Urinary pH changes
- Renal tubular excretion changes
- Renal blood flow changes