PK calculations

Question 1

clearance

Answer 1

Clearance
Clearance (Cl) is the only parameter that determines the maintenance dose rate required to achieve a target plasma concentration (and therefore effect) at steady state

Question 2

Vd

Answer 2

Volume of Distribution
Volume of distribution (Vd) is an essential determinant of drug half-life, as t1/2 = 0.693 * Vd/Cl. What this means is that for 2 drugs with the same clearance, but different voluymes of distribution, the bigger volume with have a longer half-life.

Question 3

bioavailability

Answer 3

Bioavailability
Fraction of unchanged drug reaching the systemic circulation (F). For intravenous dosing: F = 100%. For oral dosing: F depends on Absorption and Clearance

Question 4

typical in vivo PK experiments

Answer 4

IV Bolus Dose
Administer a Fixed Dose
Take serial blood samples
Analyse drug plasma levels

Oral Dose
Administer a Fixed Dose (Sometimes greater than IV)
Take serial blood samples
Analyse drug plasma levels

Question 5

AUC using the trapezoid method

Answer 5

AUC (t1-t2(= C1-C2/2 X (t2-t1)
auc total is all
units: ng.ml/min

Question 6

volume of distribution

Answer 6

units: L,ml, L/kg
if kd and clearance are known just rearrange cl= k x kd