PHAR 7632 Spring 1999

Biopharmaceutics

OU HSC College of Pharmacy

Final Exam 5 May 1999 - Answers - Section 3 Q3

Q 3.3 (10 points) Given that you want to maintain plasma concentrations above 2.5 mg/L for 12 hours, what IV bolus dose would be needed if t1/2 = 3.8 hr and V = 68.6 L? Assume a one compartment linear pharmacokinetic model. What would the expected Cp0 value be if this dose were given.

Cp = Cp0•e-kel•t = (Dose/V) • e-kel•t

Note: kel = ln2/3.8 = 0.182 hr-1

2.5 = (Dose/68.6) • e-0.182 x 12

Dose = (2.5 x 68.6) / e-2.184 = 1523 mg

Cp0 = 1523 / 68.6 = 22.2 mg/L