GBP10

Question 1

When are interactions more likely to happen

Answer 1

Poly pharmacy

Conditions eg Renal impairment

Question 2

What resources are available to check interactions

Answer 2

Pharmacist should check in hospital
BNF
Stockleys drug interactions (best)
Computer alerts

Question 3

What four pharmacokinetic mechanisms might the drug interaction involve

Answer 3

Absorption
pH change
Bonding
GI motility

Question 4

What is the MDRI and what is it relevant to

Answer 4

Multiple drug resistance transporter- responsible for getting rid of a drug by pumping it back into gut lumen
Induced by eg rifampicin means that drug plasma conc decreases
Inhibition by eg verapamil increases plasma conc of drug

Question 5

What effect does tetracycline have related to absorption

Answer 5

Binds to fe and ca salts and intercalated stopping absorption

Question 6

What drug interaction involves pH

Answer 6

Increased ph by antacids, h2 antagonists and PPIs may influence absorption of acidic drugs as they become charged

Question 7

What is the drug interaction with colestyramine

Answer 7

Binds bike in fit but also other drugs like digoxin and stops reabsorption.

Question 8

What drug influences GI motility

Answer 8

Metaclopramide increases motility so increases rate of absorption of other drugs (paracetamol can act faster)

Question 9

What are the two possible interactions with CYP mediated metabolism

Answer 9

Inhibition - increases plasma level

Induction- except CYP2D6- increases metabolism

Question 10

What drugs are inducers

Answer 10

Barbiturates 
Rifampicin 
Phenytoin 
Carbamepazine 
ethanol 
St. John's wort

Question 11

What drugs are inhibitors

Answer 11

Erythromycin 
Cimetidine 
Grape fruit juice 
Antifungals
Ciclosporin

Question 12

Which is faster inhibition or induction and why

Answer 12

Inhibition because it is a simple interaction, induction means an enzyme needs to be unregulated

Question 13

What is the drug that is known to make clopidogrel less effective and why

Answer 13

Omeprazole both transformed by same cyto.p450 clopidogrel no longer converted to active form

Question 14

What does renal elimination have to do with drug interactions

Answer 14

Competition for weak acid or base transporters so compete for elimination

Question 15

What is the interaction between NSAIDS and methotrexate

Answer 15

Compete for renal elimination

Question 16

What is a drug interaction

Answer 16

Occurs when the effects of 1 drug are changed but the presence of another drug food drunk or environmental chemical agent