Pharmacology: Pharmacokinetics II Flashcards Preview

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Flashcards in Pharmacology: Pharmacokinetics II Deck (15):
1

How can you measure drug accumulation?

1/(Fraction lost in one doing interval)

2

What is the accumulation factor for a drug given once every half life?

2 because (1/(1/2)) = 2

3

What does the accumulation factor predict?

The ratio of steady state concentration to concentration following the first dose.

4

How can you predict the peak dose concentration after a new dose during steady state?

It will be equal to (1st dose peak concentration)*(Accumulation Factor)

5

What does it mean if a drug has high bioavailability?

Drug metabolism is very low and lots of it gets to the blood stream.

6

How do you calculate bioavailability?

F=f(1-ER) where F=bioavailability, f=gut absorption, and ER = extraction ratio (how much drug the liver destroys)

7

How long does it take to reach steady state?

4-5 half lives, no matter how much you give

8

Where should your target concentration be?

Produces at least 1/2 the greatest possible therapeutic effect but no more than 5-10% of patients have toxic effects

9

How do you calculate the dosing rate?

(CL)(Css) where Css = [drug] at steady state

10

What does the dosing rate tell you?

How many mg of drug you need to give to make up for what you lose in a day

11

Normal clearance

(.693 x Vd) / t(1/2)

12

How do you determine the maintenance dose?

(Dosing rate)(Dosing interval)

13

When should you consider constant drug infusion?

When the drug half-life < 4 hours or it has extensive first pass hepatic metabolism

14

How do you calculate how much drug to give a patient that needs that drug immediately?

Loading dose = (Vd)(Target Concentration)

15

Clearance

(Ke)(Vd) where Ke = elimination rate