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