10 -Medicine interactions

Question 1

Why is liver metabolism important in drug interactions

Answer 1

Many are based on altered drug metabolism in the liver

Question 2

What is a drug interaction

Answer 2

A drug interaction is a change in one drug’s effect when it is administered with another drug, food or substance

Question 3

What is a substrate?

Answer 3

An agent that is metabolized by an enzyme into a metabolic end product and eventually excreted

Question 4

Inhibitors?

Answer 4

Interfere with an enz ability to metabolise a substrate

Question 5

Inducer

Answer 5

Increases production of enzymes responsible for metabolzing substrate > reduced conc of drug > reduced effect

Question 6

Time course of inhibitors

Answer 6

Enzyme inhibitors cause a rapid increase in blood levels of substrate (hours).

Question 7

With enz inhibitors what is the time to maximal drug interaction determined by?

Answer 7

1. The HL and time to SS of the inhibitory drug

2. The time to new steady state of the substrate

Question 8

Time course of enz inducers?

Answer 8

Requires enz SYNTHESIS so is slow - days to weeks to both reach SS max effect AND to wear off

Question 9

Serotonin syndrome?

Answer 9

agitation 
sweating
diarrhoea 
fever
shivering