Pharmacokinetics 5

Question 1

Digoxin Case Study

Answer 1

Digoxin acts on cardiac muscle but perforates it slowly. Cardiac muscle forms second compartment. Conc in 2nd compartment shows clinical effect (thus it doesn’t matter if concs in compartment 1 are very high). Blood samples taken too soon after dosing will be misleading as equilibrium will not be reached

Question 2

Lignocaine Case Study

Answer 2

Rapid entry to cardiac muscle (cardiac muscle = 1st compartment). Samples taken from blood taken at any time should represent clinical effect

Question 3

How to find T1/2 Beta on graph

Answer 3

Draw straight line through last 3 point on graph to T0 (vol at T0 = initial conc). Use y-axis and draw line out from half of original conc until it intersects line. Reference where line is intersected to the x axis

Question 4

Relationship between absorption rate (Ka) and peaks

Answer 4

Lower absorption rate = lower peaks shifted to right