Calculation of Drug Concentration

Non-Uniform Multiple Oral Dose Regimen

A patient is started on a drug at an oral dose of 500 mg at time zero, 125 mg at 7 hours and 300 mg at 11 hours (makes no sense but a nice random regimen :- all times are from time zero). Using the data shown in the table below calculate the drug concentration at 24 hr after the first dose time. Assume a one compartment linear model applies to this drug in this concentration range.

Concentration versus Time after a Single 100 mg dose

Time (hr) Concentration (mg/L)

0 0

1 2.96

2 3.35

3 3.18

4 2.92

5 2.66

6 2.42

7 2.2

8 2

9 1.82

10 1.65

11 1.5

12 1.36

13 1.24

14 1.12

15 1.02

16 0.927

17 0.842

18 0.765

19 0.695

20 0.632

21 0.574

22 0.521

23 0.474

24 0.43

Concentration versus Time after a Single 100 mg dose
Time (hr)	Concentration (mg/L)
0	0
1	2.96
2	3.35
3	3.18
4	2.92
5	2.66
6	2.42
7	2.2
8	2
9	1.82
10	1.65
11	1.5
12	1.36
13	1.24
14	1.12
15	1.02
16	0.927
17	0.842
18	0.765
19	0.695
20	0.632
21	0.574
22	0.521
23	0.474
24	0.43

The equation:

Cp after non uniform multiple dose regimen

Equation 15.4.1 Drug Concentration during a Multiple Dose Regimen (Non-Uniform Regimen)

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