Estimate Elimination Rate Constant - Example Calculations

Effect of Renal Function on Drug Excretion

A male patient is to receive Drug9 and it is known that the elimination of this drug depends on renal function. This patient is 70 kg (154 pound), 178.3 cm (70.2 inches) height and 39 years old. The measured serum creatinine was 1.38 mg/dl. Calculate the creatinine clearance for this patient using the Cockcroft and Gault equation. (Note: Use ideal body weight if less than actual body weight). Once you have the calculated creatinine clearance for this patient estimate the expected elimination rate constant for Drug9 in this patient.

A previous study with Drug9 resulted in the following data.

t1/2 (hr) Creatinine
Clearance (ml/min)
2.8610
1.8150
1.1120

Linear graph paper


NOTE: Clicking either of the button 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 [# 2590620347]. 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:

kel =

Equation 27.1.1 Elimination rate constant calculated from creatinine clearance


Estimate CrCl from urine collection

Equation 27.1.2 Creatinine Clearance calculated from a timed urine collection

UCr is the concentration of creatinine in urine in mg/dl, Vu is the volume of urine in ml, SCr is the serum creatinine concentration in mg/dl and t is the collection time in minutes.


Cockcroft and Gault equation for CrCl

Equation 27.1.3 Cockcroft and Gault equation for estimating Creatinine Clearance

Weight in kg and SCr is the serum creatinine concentration in mg/dl. Note, you should only multiply by 0.85 in the case of female patients. The original authors of this equation used actual body weight in Equation 27.1.3. More recently it has been recommended that ideal body (IBW) be used in this equation unless the actual body weight (ABW) is less. (Murphy, 2001, p4).

IBW (male) (kg) = 50 + 2.3 x (Ht(in) - 60) or IBW (female) (kg) = 45.5 + 2.3 x (Ht(in) - 60) (Murphy, 2001, p4-5)


References
Last update: Tue 7 Apr 2020 06:14:45 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 © 2002-2020 David Bourne (david@boomer.org)