Time (hr) | Cp (mg/L) |
2 | 0.452 |
3 | 0.278 |
4 | 0.165 |
6 | 0.063 |
8 | 0.023 |
10 | 0.009 |
12 | 0.003 |
Estimate kel, t_{1/2}, V, and Cl.
You will have one chance to submit your answers for this problem [# 2440429224]. 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.
Equation 15.3.1 Drug concentration, Cp, after an IV infusion
The table above provides a set of data for you to analyze. Using these data you should be able to estimate the elimination rate constant (kel), the elimination half-life (t_{1/2}), the apparent volume of distribution (V) and the total body clearance (CL) for the drug. First graph the data on semi-log graph paper and put a straight line thorugh the data. A best fit line. Don't try to put the line through any particular point but through all the data. The best fit line may not go through any of the points. A clear ruler helps. Then you can see the points above and below the line to get a good balance. Draw the line. Estimate the intercept on the left and right extreme of the line. Use these extreme points from the line to estimate kel from the -slope (using the natural log, ln, version) as:
Now you can either pick one of the concentrations (from the line) and substitute into the equation above to find V. Alternately you could extrapolate the 'best-fit' line back to the end of the infusion, not the y-axis (time zero).
Equation 15.3.2 Cp^{D} at the end of the infusion period, T
With an estimate of Cp^{D} it is possible to rearrange Equation 15.3.2 and calculate V, the apparent volume of distribution:
Equation 15.3.3 V estimated from Cp^{D} data