dosage calculation

Question

You provide the manufacturer’s recommended dose of the new antiseizure drug, “Seizstop”, which is 10mg/kg IV for a 100kg patient.  You then draw a level 30 minutes after the dose. Assume rapid distribution and neglible clearance/metabolism over the 30minute period between the time of administration and drug level assement. 

3. The serum level of “Seizstop” returns at 83.3mg/L. What is the volume of distribution of the drug?

            A.  1.6 Liters  

            

            B.  16 Liters

            C.  12 Liters

            D.  1.2 Liters

            E.  8 Liters

4. Assume the goal therapeutic serum level of a is 120 mg/L.  How much more drug do you need to order to attain this level.  

A. 60mg

B.  300mg

C.  45 mg

D.  450mg

E.  600mg 

 5.  A patient with chronic kidney disease has a vancomycin serum level drawn that returns at 37mcg/mL. She will require a redose when the level reaches 15mcg/mL.  Her half-life has been determined to be 46 hours. How many hours  after the initial serum  draw will she require a redose. 

A.  52 hours

B.  60 hours

C.  67 hours

D.  73 hours

E.  80 hours

6.  You need to check a serum trough level of tacrolimus that was started a transplant patient. This level will need to be drawn at steady state.  Assuming a half-life of 12hours, after how many hours would it be appropriate to setup a trough level. 

A. 24 hours 

B. 36 hours

C.  42 hours

D. 48 hours

E. 60 hours

Answer 1

3.Vd = dose/concentration

Dose = 10 mg/kg x 100kg = 1000 mg

Vd = 1000 / 83.3 = 12 L = C

4.Vd = dose/concentration

12 = x / 120

x = 1440

1000 - 1440 = 440 --> 450 mg = D

6.Steady state = 5 x half life

5 x 12 = 60h = E