AI- pharmacokinetics/dynamics of intravenous contrast media

Question 1

what is PK ?

Answer 1

PK is the discussion of how the body interacts for the period of exposure (in this
case contrast media)

Question 2

what is pd

Answer 2

how the drug effect on the body from perspectives of:
* Absorption
* Distribution
* Metabolism
* Excretion

Question 3

intravenous contrast is visible in places not normally expected, why ?

Answer 3

specific changes to anatomy/physiology due to disease

Question 4

define absorption in this context

Answer 4

the process that brings a drug from administration into circulation

Question 5

define absorption in terms of speed and concentration

Answer 5

absorption defines the speed and concentration at which a drug arrives at its location

Question 6

why is IV contrast rapid ?

Answer 6

BECAUSE IV CONTRAST MEDIA IS NOT ABSORBED THIS IS VERY RAPID

Question 7

Define distribution in this context

Answer 7

Distribution describes how a drug is spread through the body

• Physiology of the individual
• Fluid status of the patient
• Body habitus

Question 8

define metabolism in this context

Answer 8

Metabolism describes onward processing of the drug by the body into subsequent compounds

Question 9

define excretion in this context

Answer 9

The process where the drug is eliminated by the body
Most frequently this is the kidneys

Question 10

where is drug excretion also experienced

Answer 10

LUNG, SKIN or GI TRACT

Question 11

how many stages are there post introduction of iv contrast ?

Answer 11

5

Question 12

list the stages of the introdcution of iv contrast

Answer 12

1. Contrast begins to gather in the vessels
   (usually venous hence IV!) but
   immediately starts to be carried away
2. The injection pump, with time,
   administers enough contrast so the
   blood is mainly a ‘bolus’ of contrast
3. The contrast bolus moves from
   the injection site to the heart
   where blood from elsewhere in
   the body mixes and dilutes as it
   passes through the lungs

4.The contrast enhanced
blood returns to the heart
then is pushed through the
wider circulation to both
dilute but enhance
structures it passes into

5.Where there is no
specific pathology to
show the contrast begins
to be excreted via the
kidneys thus starting the
clearance effect

Question 13

why must we time our iv contrast examinations ? hint multiple different stages

Answer 13

This means we are losing contrast density
continuously throughout the stages

Question 14

why does contrast allow us to see tumours?

Answer 14

-Where tumours form or there are
collections or infection, there is a
circumference of angiogenesis or blood
vessel formation.

-This ‘capsule’ means there is an area of
increased number of micro blood
vessels that becomes visible when
flushed by IV contrast

Question 15

what are some potentially dangerous response to iv contrast

Answer 15

mild:
Rash
Urticaria/Hives
Itching

severe:
Respiratory arrest
Hypotension
Cardiac arres