Calculation of Parameters from a Given Data Set

The Data

After an I.V. Bolus Dose of 500 mg

Time Interval(hr) Volume of Urine Collected (ml) Concentration in Urine (µg/ml) <----------------> <----------------> <---------------->






0-2 120 320


2-4 130 210


4-6 125 170


6-9 no sample



9-12 200 45


12-15 190 30


Complete the Table

Time Interval(hr) Volume of Urine Collected (ml) Concentration in Urine (µg/ml) U (mg) tmidpoint (hr) U/t (mg/hr)






0-2 120 320 38.4 1 19.2
2-4 130 210 27.3 3 13.65
4-6 125 170 21.75 5 10.63
6-9 no sample



9-12 200 45 9 10.5 3
12-15 190 30 5.7 13.5 1.9

Graphing the Data

Plot U/t versus tmidpoint on semi-log graph paper.

The Parameters

Intercept by inspection after putting a line through the data on semi-log graph paper = 24.5 mg/hr

kel from the -ve slope of ln-linear line through the data. Note the R/E on the line at 14 hours is 1.68. NOTE:: This value and the value for R/E will depend on where you put the line. Everyone may put the line in a different place.

Since the Intercept = ke x Dose = 24.5 = ke x 500

ke = 24.5/500 = 0.049 hr-1

Since km = kel - ke = 0.191 - 0.049 = 0.142 hr-1

fe = ke/kel = 0.049/0.191 = 0.257

fm = km/kel = 0.142/0.191 = 0.743

Summary

Parameter Value Unit
kel 0.191 hr-1
ke 0.049 hr-1
km 0.142 hr-1
fe 0.257
fm 0.743