Determination of the Pharmacokinetic
Parameters (cont'd)

2- Area under the curve

The trapezoidal rule:

a- Plot the plasma conc measured after administration of single oral dose of the drug.

b- Connect the plasma concentrations by straight lines, and divide the plasma profile to trapezoids.

0,0
1
Cp1, t1
2
Cp2, t2
3
Cp3, t3
4
Cp4, t4
5
Cp5, t5
6
Cp6, t6
tail

c- AUC = area of trapezoid 1 + area of trapezoid 2 + area of trapezoid 3 + ... etc.

Area of a Trapezoid =

(Cpn + Cpn+1)

2 .(tn+1 - tn)

Area of the last trapezoid (tail of the curve):

=

last concentration

k =

Cp6

k
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