Constant rate regimen -3 Flashcards
Constant-rate regimen
The drug is administered systemically at a constant or ___ rate.
zero order
Constant-rate regimen
Constant plasma concentration can be best accomplished by ___ drug at a constant rate
* IV infusion via infusion pump
* Orally administered drugs: slow-release tablets
* Transdermal patches
infusing
Why constant-rate regimen
IV bolus dose is eliminated ____. Want something that will last in the therapeutic window longer, a ___ state
rapidly, steady
Css is equal to
R0/CL
infusion rate/clearance
before reaching steady state
infusion equation
after stopping infusion
What is the infusion equation after stopping
Practice questions
Given IV infusion at 2 mg/min, what is plasma concentration at steady state? Vd=10 L, K = 1.4 /h
A
Practice questions
After steady state is reached with 1 mg/min, you increase the dose to 2
mg/min. What would be the new steady state concentration? Vd=10 L, K = 1.4 /h
A
4.3 x 2 = 8.6
Practice questions
After 1 h of infusing drug X at 1 mg/min, you increase the dose to 2 mg/min. What would be the concentration at steady state? Vd=10 L, K = 1.4 /h
B
4.3 x 2 = 8.6
After 1 h of infusing drug X at 1 mg/min, you want to increase Cp to 9
immediately. What can you do? Vd=10 L, K = 1.4 /h
IV Bolus dose = Vd x Cp
10 L x (9-3.2 ug/mL) = 58 mg
B
Css = 1 mg/min / (10 L x 1.4 /h) = 4.3 ug/mL
T or F: Combining IV infusion with an IV bolus loading dose can maintain Cp near Css from the beginning of drug administration
true
Practice questions
T or F: The time to reach the steady state depends on the dose.
False
T or F: Doubling the dose will double the steady state concentration.
True
T or F: Doubling the dose will shorten the time to reach a steady state.
False
