Calculation of Drug Concentration

Non-Uniform Multiple Oral Dose Regimen

A patient is started on a drug at an oral dose of 125 mg at time zero, 100 mg at 3 hours and 50 mg at 5 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 1.67

2 1.43

3 1.12

4 0.862

5 0.664

6 0.512

7 0.395

8 0.305

9 0.235

10 0.181

11 0.14

12 0.108

13 0.083

14 0.064

15 0.0494

16 0.0381

17 0.0293

18 0.0226

19 0.0174

20 0.0135

21 0.0104

22 0.008

23 0.00617

24 0.00475

Concentration versus Time after a Single 100 mg dose
Time (hr)	Concentration (mg/L)
0	0
1	1.67
2	1.43
3	1.12
4	0.862
5	0.664
6	0.512
7	0.395
8	0.305
9	0.235
10	0.181
11	0.14
12	0.108
13	0.083
14	0.064
15	0.0494
16	0.0381
17	0.0293
18	0.0226
19	0.0174
20	0.0135
21	0.0104
22	0.008
23	0.00617
24	0.00475

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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