Clinically Relevant Drug Interactions (DONE) Flashcards Preview

PH3110 > Clinically Relevant Drug Interactions (DONE) > Flashcards

Flashcards in Clinically Relevant Drug Interactions (DONE) Deck (14):
1

What is an interaction?

An interaction occurs when the effects of one drug are changed by the presence of another drug, food, drink or by some other chemical agent

2

What is the role of the pharmacist re. drug interactions?

Anticipate the interactions before they occur
Recognise them if they occur
Counsel patients on their therapy

3

What are the contributing factors to drug interactions?

Drug characteristics- are they susceptible to interactions/ do they commonly cause interactions
Patient characteristics
Polypharmacy including self medication

4

Give some examples of risky drugs re. interactions

Drugs with potential to cause problems with the handling of other drugs e.g. enzyme inhibitors, enzyme inducers
Drugs causing issues in under or overdose
Drugs with a long half life e.g. amiodarone

5

What are the possible mechanisms of interactions?

Pharmacokinetic (ADME)
Pharmacodynamic- additive or synergistic, antagonistic or opposing, changes in transport mechanisms, disturbed electrolytes

6

Describe metabolism interactions of drugs

Most important pathway of metabolism is hepatic, specifically cytochrome P450
Significant interactions occur when the enzymes are induced or inhibited

7

Describe the characteristics of enzyme induction and give some examples of drugs affected

Carbamazepine, phenytoin, Griseofulvin, rifampicin
Work by increasing amount of ER in hepatocytes
Takes two to three weeks to occur

8

Describe the characteristics of enzyme inhibition and give some examples of drugs affected

Amiodarone, quinolones, allopurinol, imidazoles
Decrease in metabolism, leads to increase in concentration
Potentially lethal
Warn patients of toxic signs of risky drugs

9

Which drugs should not be taken in someone with an acute kidney injury if they become ill after a few days?

Diuretics
ACEIs
Metformin
NSAIDs

10

What are the different types of pharmacodynamic interactions?

Additive or synergistic
Antagonistic or opposing
Changes in transport mechanisms
Disturbed electrolytes

11

Give examples of drugs with a narrow therapeutic index and the side effects of each

Phenytoin- ataxia, diplopia, epileptic seizures
Digoxin- nausea, vomiting, anorexia
Lithium- non-specific toxicity
Theophylline- nausea, anorexia, trembling, sleeplessness, convulsions

12

Give examples of drugs that don't have a narrow therapeutic index but can still cause problems in overdose

Sulphonylurea hypoglycaemics
Ciclosporin
Cytotoxics
MAOIs

13

What are the most important patient characteristics for interactions?

Health and age

14

What is polypharmacy?

Taking large numbers of drugs at the same time
Contributes to ADRS, especially in the elderly
New drugs often added without assessing the existing regime