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PharmD clinical pharmacy program Level 3, Semester 2 Biopharmaceutics & Pharmacokinetics (PT608(
3. A physician wants to administer an anesthetic agent at a rate (R) of 2 mg/h by IV
-1
infusion. The elimination rate constant (K) is 0.1 h and the volume of distribution
(one compartment, Vd) is 10 L. How much is the drug plasma concentration (µg/mL)
at the steady state? What loading dose should be recommended to reach steady state
immediately?
ANSWER
=
/
. = = / = µ /
.
To reach Css instantly,
-1
-1
b. DL = = 2mg.h / 0.1h = 20 mg
4. What is the concentration of a drug at 6 hrs after infusion administration at 2 mg/h,
with an initial loading dose of 10 mg (the drug has a t ½ of 3 hrs and Vd of 10 L)?
ANSWER
-1
k=0.693/t½ = 0.693 / 6= 0.231 h
= − + ( − − )
− −
= − . + ( − − . )
. −
= 0.9mg/L =0.9µg/mL
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