Review of PK Questions 2023. Postgraduate Students

1.

Review of PK Questions
Postgraduate Students

2.

Question 1
• *-A 78 kg, 28 year old man is receiving phenytoin tablets for the
treatment of seizures. When this patient was taking a daily oral dose of
250 mg phenytoin, his steady state plasma concentration was 7.2
mg/L. Because phenytoin plasma concentration was well below the
therapeutic range, the patient daily dose was increased to 450 mg
which resulted in steady state plasma concentration of 30 mg/L.
phenytoin bioavailability is 100% and the Vd is 50 L. The data
presentation was as following.

3.

Question 2
Graphically the patient Vmax (mg/day) will be
a-10
b- 600
c- 34.72
d- 15
Graphically the patient Km (mg/L) will be?
a-10
b- 600
d- 15
c- 34.72
What is the daily phenytoin dose (mg/day) that should achieve a
steady state phenytoin plasma concentration of 20 mg/ L in this
patient?
a-400
b-300
c-280
d-350

4.

Question 2
What is the creatinine clearance for a 25 years
old male patient with a S Cr of 1 mg/dL? The
patient is 5 ft, 4 inches in height and weighs
103 kg.

5.

Question 1

6.

Question 2
Assume the flow rate of blood to the dialysis machine is 350
mL/min. By chemical analysis, the concentrations of drug
entering and leaving the machine are 30 and 12 g/mL,
respectively. What is the dialysis clearance?

7.

Question 2

8.

Question 4
LM is an epileptic patient being treated with phenytoin. He has
hypoalbuminemia (albumin = 2.2 g/dL) and decreased renal
function (creatinine clearance = 12 mL/min). His total
phenytoin concentration is 7.5 mg/L. Compute the estimated
normalized phenytoin concentration for this patient.

9.

Question 4

10.

Question 5
C.M. is a 55-year-old man who is initiated on phenytoin tablet
after a craniotomy. His current steady-state phenytoin
concentration is 6 mg/L at a dose of 200 mg/day by mouth. If
his affinity constant (Km) is calculated to be 4 mg/L, what will
be the new steady state concentration if the tablet dose is
increased to 450 mg/day?

11.

Question 5

12.

Question 6
K.M., an 80-year-old white man (66 kg, 64 inches), is admitted
to the hospital for kidney impairment. He has a history of atrial
fibrillation and congestive heart failure taking lisinopril 10
mg/day by mouth, procainamide 125 mg/kg/day, furosemide
40 mg/day. On admission, his serum Cr is 0.92 mg/dL. K.M. was
initiated on the following drugs: trimethoprim/
sulfamethoxazole intravenously, 240 mg of trimethoprim every
12 hours. If 85% of procainamide is excreted unchanged by
kidney, what will be the new recommended dose?

13.

Question 6

14.

Question 7
After IV injection of 1200 ug of a drug to a patient, the
following data were obtained (t1/2= 1.5hr), Calculate
the percent of metabolic clearance in this patient
Collection interval (day)
Urine volume( L)
Urine concentration(ug/L)
0-1
1
225
1-2
1.2
123
2-3
1.4
68
3-4
1.1
56
4-5
1.3
31
5-7
2.5
17
7-8
1.1
0