Estimate Renal Clearance from Urine versus Time Data
IV Bolus - Linear One Compartment
Using the Rate of Excretion versus Cp Plot
with suggestions from Sukyung Woo, PhD
A dose of 50 mg was administered intravenously to a healthy volunteer. Total urine samples were collected after 2, 4, 6, 8, 10, 12, 18 and 24 hours. Samples were well mixed and analyzed for drug concentration. The volume of each sample was also recorded. During the study, plasma sample were collected at the midpoint (Tmid) of each collection period. The collected data are shown in the table below.
| Urine Data |
Plasma Data |
|
Time (hr)
|
Urine Volume (ml)
|
Cu (mg/ml)
|
Tmid (hr)
|
Cp (mg/L)
|
|
2 |
66 |
0.222 |
1 |
1.8 |
|
4 |
64 |
0.137 |
3 |
1.08 |
|
6 |
58 |
0.09 |
5 |
0.645 |
|
8 |
70 |
0.045 |
7 |
0.385 |
|
10 |
71 |
0.026 |
9 |
0.231 |
|
12 |
66 |
0.017 |
11 |
0.138 |
|
18 |
183 |
0.007 |
15 |
0.0494 |
|
24 |
216 |
0.001 |
21 |
0.0106 |
The table above provides a set of data for you to analyze. Using the plasma data, plot the Cp-time data on a semi-log graph and estimate the overall elimination rate constant, volume of distribution, and total clearance for the drug. Using the urine data, first calculate the amount of unchanged drug excreted during each time interval and then the cumulative amount excreted upto that time point, U. Calculate the rate of excretion during each interval. A plot of the rate of excretion against the corresponding plasma concentration in a linear graph yields a straight line with a slope equal to renal clearance.
Your objective is to estimate kel, total CL, fe, CLr, CLm and ke.
NOTE: Clicking either of the two buttons above
will prevent you getting credit for this problem
To get credit for this problem print this page, work the problem and
You will have one chance to submit your answers for this problem [# 1150543585]. You can try the homework problem more than once with different data to improve your grade. Your highest score is recorded. After submitting your answers you can use the browser back arrow to get back here and see how the compuer worked the problem.
Some Equations:
Equation 12.3.1 Total Clearance
Equation 12.3.2 Renal Clearance
Equation 12.3.3 Fraction Excreted Unchanged
Equation 12.3.4 Renal Clearance and Excretion Rate Constant
Equation 12.3.5 Metabolic Clearance
Equation 12.3.6 Metabolic Rate Constant
Last update: Sat 27 Jul 2024 08:10:07 pm
Privacy Statement - 25 May 2018
Material on this website should be used for Educational or Self-Study Purposes Only
iBook and pdf versions of this material and other PK material is available
Copyright © 2002-2024 David Bourne (david@boomer.org)