2- Polypharmacy and the considerations when multiple drugs are administered concomitantly

Question 1

Define summation

Answer 1

The combined effect of 2 drugs produces a result that equals the sum of the individual effects of each agent

Question 2

Define potentiation

Answer 2

When a drug on its own does not have an effect but may be affected in combination with another drug

Question 3

Define synergism

Answer 3

Drug combinations produce a therapeutic or toxic effect greater than sum of each drugs action

Question 4

Name 3 chemical (pharmaceutical) effects/factors that you need to consider when mixing drugs

Answer 4

pH - stability of drug is often pH dependent
Oxidation/reduction reactions
Complex formation
Inactivated by certain vehicles

Question 5

How can drug-drug interactions affect the distribution of a drug?

Answer 5

Competition plasma protein binding
Some drugs reduce blood flow to tissue (reduced absorption)
Reduced clearance

Question 6

How can drug-drug interactions affect the metabolism of a drug?

Answer 6

Inhibit/induce liver enzymes (CYP P450)

Question 7

List 2 drugs that inhibit liver metabolism

Answer 7

Chloramphenicol, Omeprazole, Propofol, Cimetidine, Anti-fungals

Question 8

List 2 drugs the induce liver metabolism

Answer 8

Barbiturates, Carbamazepine, Cyclosporin

Question 9

Why are NSAIDs & steroids contraindicated?

Answer 9

Increased risk of GI ulceration

Question 10

Why are NSAIDs & aminoglycosides contraindicated?

Answer 10

Increases risk of nephrotoxicity

Question 11

List 2 types/forms of adverse effects

Answer 11

Lack of efficacy
Exaggerated normal response
Hypersensitivity
Toxic effects
Idiosyncratic