Question

A patient received a single dose of 500 mg erythromycin
in the form of a tablet that is known to have 80%
bioavailability. Calculate the time to reach the maximum
concentration (1.7 hr), the maximum conc (7.91 mg/L).
AUC (50) and Clearance (8 Uhr) after this single dose fK
is 0.2 hrl, Ka is 1.3 hr. and Vd is 40 liters.​

Answer 1

Answer:

A patient who has had an adverse reaction to Drug X requires that the plasma drug

concentration not ever exceed 40 mg/L. If Drug X has half life of 8 hrs and clearance of 4 L/hr,

what is the best i.v. loading dose that will give the maximum blood levels but still avoid an

adverse reaction (5pts)?

A. 2500 mg

B. 2200 mg

C. 2000 mg

D. 1700 mg

E. 1000 mg

t1/2 = ln2*V/CL ÎV = 8 hr*4 L/hr/ln(2) = 46.2 L;

V = D/Co ÎDose = 46.2 L * 40 mg/L = 1847 mg; Thus, answer D.