AUC Concepts Dr Arthur Roberts Objectives Elimination Rate

AUC Concepts Dr. Arthur Roberts

Objectives • • • Elimination Rate Half Life Volume Distribution Clearance AUC

Review

Review

Elimination ? log plot ln C 0 Plasma Drug Concentration non-log plot time slope = - elimination rate constant or – slope = elimination rate constant

Elimination Rate Constant (K) slope = - elimination rate constant or – slope = elimination rate constant =K ln C 0 K ln C

Elimination A B Which one has the higher elimination rate?

Plasma Prediction

Half-Life ln 2 K=Elimination Rate Constant Show an example of half life calculated from 2 plasma concentrations.

Half-Life • individuals • disease

Distribution and Elimination Phases Distribution Phase Elimination Phase

Volume Distribution 10 mg Measure Concentration 1 mg/ml What is the volume ?

Volume Distribution 10 mg Measure Plasma Concentration 0. 002 mg/ml = 2 mg/L What is the volume ?

Clearance and Elimination Rate Constant • Clearance= Volume of plasma with drug removed per time. (Volume/Time) • model-independent Clt= Systematic Clearance V= Volume Distribution K= Elimination Rate Clearance

AUC (Area Under the Curve)

AUC (Area Under the Curve)

Trapezoidal Rule

AUCC 0 -infinity C 0 K Clast AUCC 0 to Clast AUCC 0 -infinity = AUCC 0 to Clast + terminal area

AUC A ln [Drug] AUC Area for A < AUC Area for B AUC time ln [Drug] B AUC time Which one has increased clearance?

Example

End of AUC Concepts