Calculation of Drug Concentration

Non-Uniform Multiple Oral Dose Regimen

A patient is started on a drug at an oral dose of 250 mg at time zero, 400 mg at 6 hours and 125 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 9.7

2 9.1

3 7.77

4 6.57

5 5.55

6 4.69

7 3.96

8 3.34

9 2.82

10 2.39

11 2.01

12 1.7

13 1.44

14 1.21

15 1.02

16 0.865

17 0.731

18 0.617

19 0.521

20 0.44

21 0.372

22 0.314

23 0.265

24 0.224

Concentration versus Time after a Single 100 mg dose
Time (hr)	Concentration (mg/L)
0	0
1	9.7
2	9.1
3	7.77
4	6.57
5	5.55
6	4.69
7	3.96
8	3.34
9	2.82
10	2.39
11	2.01
12	1.7
13	1.44
14	1.21
15	1.02
16	0.865
17	0.731
18	0.617
19	0.521
20	0.44
21	0.372
22	0.314
23	0.265
24	0.224

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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