Exam 2 Multiple Dosing

Question 1

Why is multiple dose regimen needed?

Answer 1

when the drug concentration falls below the therapeutic range, the patient needs another dose

Question 2

When given an IV bolus, how do you calculate the plasma concentration associated with each dose?

Answer 2

just add up the concentration of the doses for a given time after the first dose

Question 3

What is the max and min of the plasma drug concentration graph when given the graph?

Answer 3

the max is the peak and the min is the trough

Question 4

What is tau?

Answer 4

the dosing interval

Question 5

How does dosing interval (tau) relate to fluctuation?

Answer 5

the larger the dosing interval (tau), the greater the fluctuation

Question 6

Frequent drug administration leads to what kind of fluctuation?

Answer 6

small fluctuation (since smaller the tau, smaller the fluctuation)

Question 7

Frequent drug administration leads to what kind of accumulation?

Answer 7

more accumulation (smaller the tau, smaller the fluctuation, larger the accumulation)

Question 8

True/false: Higher dose is expected to show greater drug accumulation (higher accumulation index)

Answer 8

false

Question 9

What is the difference between IV infusion and IV bolus multiple dosing?

Answer 9

IV infusion is given to the patient all at once while IV bolus multiple dosing involves multiple doses of the medication over a period of time

Question 10

What is the time to reach steady state?

Answer 10

3.3 half lives (only depends on the half life of the drug)

Question 11

What is average concentration (Css,ave)?

Answer 11

the concentration that gives AUCss when maintained for tau

Question 12

The same amount of dose administered per unit time will lead to what Css,ave?

Answer 12

the same Css,ave (the same average concentration, example is 100 mg every 10 hours and 50 mg every 5 hours give the same Css,ave)

Question 13

What is the difference between the average concentration equation for IV bolus and oral dosing?

Answer 13

oral dosing equation has bioavailability in the numerator of the equation that the IV bolus equation lacks

Question 14

When you switch dosage regimen from 10 mg q12h to 10 mg q24h, what happens to fluctuation?

Answer 14

fluctuation increases

Question 15

When you switch dosage regimen from 10 mg q12h to 10 mg q24h, what happens to average steady state concentration?

Answer 15

lower concentration

Question 16

When you switch dosage regimen from 10 mg q12h to 10 mg q24h, what happens to time to reach a new steady state?

Answer 16

same since it is determined by half life (3.3 half lives)

Question 17

When you switch dosage regimen from 10 mg q12h to 10 mg q24h, what happens to accumulation index?

Answer 17

accumulation index decreases (since tau increases, fluctuation increases, accumulation index decreases)

Question 18

When you switch dosage regimen from 10 mg q12h to 20 mg q24h, what happens to fluctuation?

Answer 18

fluctuation increases (since tau increases)

Question 19

When you switch dosage regimen from 10 mg q12h to 20 mg q24h, what happens to average steady state concentration?

Answer 19

same concentration (equation is dose/tau / CL)

Question 20

When you switch dosage regimen from 10 mg q12h to 20 mg q24h, what happens to time to reach a new steady state?

Answer 20

the same since it is determined by 3.3 half lives

Question 21

When you switch dosage regimen from 10 mg q12h to 20 mg q24h, what happens to accumulation index?

Answer 21

accumulation index decreases (since tau increases, fluctuation increases, accumulation index decreases)

Question 22

What are the steps to dosing regimen design?

Answer 22

1. know the target concentration range
2. determine the maximum dosing interval (tau max) and round to a reasonable interval (ex. q6h, q8h, q12h, and once daily)
3. determine maintenance dose (Dm) and choose Css,ave to fall in the middle of this range
4. Check whether Css,max and Css,min fall within the expected range and adjust dosing regimen (dose or tau) if they do not fall within the required range
5. if necessary, determine loading dose (Dl)

Question 23

What is the purpose of the loading dose?

Answer 23

loading dose is the first dose given to the patient and gives high enough concentration for the next doses (aka maintenance dose)