# PHAR 4634 Fall 1995 Pharmaceutics III OU HSC College of Pharmacy

## First Semester Exam 15 September 1995

### Section ONE. Sketch a Graph or Diagram - 4 x 4 = 16 points

Sketch the graphs or diagrams requested in the space provided. Include any distinguishing characteristics. Assume that a linear one compartment model applies unless otherwise specified. Include labels and units.

Q 1.1 A linear plot of Cp versus time after a single i.v. bolus dose.

3" x 2.5" space for sketch

Q 1.2 A semi-log plot of Cp versus time after an i.v. infusion of 2 hours, show Cp vs. t for 6 hours.

3" x 2.5" space for sketch

Q 1.3 A linear plot of Cumulative Amount Excreted versus time after a single i.v. bolus dose.

3" x 2.5" space for sketch

Q 1.4 A linear plot of absorbance versus concentration for a compound which follows Beerıs law.

3" x 2.5" space for sketch

### Section TWO. True/False - 10 x 2 = 20 points

Check the Correct Response.

Q 2.1 The value of e-0.45 is 1.568. True False

Q 2.2 Clearance can be thought of as a volume of plasma from which the drug is removed in a specific time period. True False

Q 2.3 If elimination from the central/body compartment is first order we can assume that a one compartment pharmacokinetic model is applicable. True False

Q 2.4 Given Cp = Cp0 x e-kel * t, and two data points (t1, Cp1) and (t2, Cp2), the elimination rate constant can be calculated as the slope [= (lnCp2 - lnCp1)/(t2-t1)] multiplied by -1. True False

Q 2.5 The integrated equation, A = B*[1- e-C*t], is consistent with plasma concentrations after an i.v. infusion has been stopped. True False

Q 2.6 The units of ln(R/E) are mg/L where R/E is rate of excretion.True False

Q 2.7 If 198 mg of a 300 mg i.v. bolus dose is excreted as unchanged drug into urine, the value of fm is 0.66. True False

Q 2.8 When looking at the effect of pH on the extraction of salicylic acid from aqueous buffer into an organic solvent a linear plot of 1/PC' versus 1/[H+] should produce a straight line plot. True False

Q 2.9 If the infusion rate constant, k0, is doubled the steady state plasma concentration, Cpss, will be doubled, assuming the other parameters are unchanged. True False

Q 2.10 Appropriate units for AUC are mg.hr.L. True False

### Section THREE Short Answer - 3 x 5 = 15 points

Remember to limit the time spent on this section to 5% of 50 minutes (approx. 2.5 minutes) per question.

Q 3.1 Briefly describe the parameter, apparent volume of distribution. Include a definition or description, a working (useful) equation, and units.

6.5" x 2" space for sketch

Q 3.2 Draw a scheme or diagram for a one compartment pharmacokinetic model (during an i.v. infusion administration) with renal and non renal elimination. Label the scheme or diagram and give the differential equations for two parts of the model.

6.5" x 2" space for sketch

Q 3.3 You have completed a drug disposition study in which you administered a drug by i.v. bolus. Plasma samples were collected at various times and assayed for drug concentration. Describe how you would calculate the total AUC

6.5" x 2" space for sketch

### Section FOUR Calculations - Total for this section = 49 points

Show all your work for full credit. All material not deleted or crossed-out will be considered for grading. Put labels and units on all requested graphs.

Q 4.1 (16 points) A 500 mg dose of a drug was given by i.v. bolus and the data below was collected. Plot the data and determine Cp0, kel, V, and Clearance from these data.

 Time hr Concentration mg/L 0.5 13.5 1.0 13.5 2.0 10 4.0 7.6 6.0 5.1

Space provided for answer. Two cycle semi-log graph paper provided.

Q 4.2 (14 points) Calculate i) a suitable loading infusion (over 30 minutes) and ii) a maintenance infusion to reach quickly and maintain a plasma concentration of 35 mg/L. Assume a one compartment pharmacokinetic model and use kel = 0.165 hr-1 and V = 18.4 L as patient parameters.

Q 4.3 (19 points) Urine samples were collected at various times after an i.v. bolus dose of 500 mg. The results are shown below. Calculate kel, ke, fe, and fm from these data.
 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

Space provided for answer. Two cycle semi-log graph paper provided.