Introduction To Pharmacokinetics

Oral Dosing - ka

A patient is given a 500 mg dose of a drug via a single oral dose.

F = 0.45        t1/2 = 1.5 hours         k = 0.462 h-1
AUC = 11.933 mgxh/L      CL = 18.86 L/h
Vd = 40.8 L                      t1/2(a) = 0.5 hours

Now you know the absorption half-life, what is the absorption rate constant (ka) of the drug?

Type in your answer to three decimal places then press the OK button.

The absorption rate constant is: h-1

Time (h)	Plasma Drug Concentration (mg/L)	C* (mg/L)	C*-C (mg/L)
0	0	8.2	8.2
0.5	2.5	6.6	4.1
1	3.2	5.4	2.2
1.5	3.1	4.2	1.1
2	2.8	3.3	0.5
3	2.0	2.1	0.1
4	1.3	1.3	0
5	0.8	0.8	0
6	0.5	0.5	0
7	0.3	0.3	0
8	0.2	0.2	0

Time (h)	Plasma Drug Concentration (mg/L)	C* (mg/L)	C*-C (mg/L)
0	0	8.2	8.2
0.5	2.5	6.6	4.1
1	3.2	5.4	2.2
1.5	3.1	4.2	1.1
2	2.8	3.3	0.5
3	2.0	2.1	0.1
4	1.3	1.3	0
5	0.8	0.8	0
6	0.5	0.5	0
7	0.3	0.3	0
8	0.2	0.2	0

Time (h)	Plasma Drug Concentration (mg/L)	C* (mg/L)	C*-C (mg/L)
0	0	8.2	8.2
0.5	2.5	6.6	4.1
1	3.2	5.4	2.2
1.5	3.1	4.2	1.1
2	2.8	3.3	0.5
3	2.0	2.1	0.1
4	1.3	1.3	0
5	0.8	0.8	0
6	0.5	0.5	0
7	0.3	0.3	0
8	0.2	0.2	0

Time (h)	Plasma Drug Concentration (mg/L)	C* (mg/L)	C*-C (mg/L)
0	0	8.2	8.2
0.5	2.5	6.6	4.1
1	3.2	5.4	2.2
1.5	3.1	4.2	1.1
2	2.8	3.3	0.5
3	2.0	2.1	0.1
4	1.3	1.3	0
5	0.8	0.8	0
6	0.5	0.5	0
7	0.3	0.3	0
8	0.2	0.2	0