Exam 2 Multiple Dosing Flashcards
Why is multiple dose regimen needed?
when the drug concentration falls below the therapeutic range, the patient needs another dose
When given an IV bolus, how do you calculate the plasma concentration associated with each dose?
just add up the concentration of the doses for a given time after the first dose
What is the max and min of the plasma drug concentration graph when given the graph?
the max is the peak and the min is the trough
What is tau?
the dosing interval
How does dosing interval (tau) relate to fluctuation?
the larger the dosing interval (tau), the greater the fluctuation
Frequent drug administration leads to what kind of fluctuation?
small fluctuation (since smaller the tau, smaller the fluctuation)
Frequent drug administration leads to what kind of accumulation?
more accumulation (smaller the tau, smaller the fluctuation, larger the accumulation)
True/false: Higher dose is expected to show greater drug accumulation (higher accumulation index)
false
What is the difference between IV infusion and IV bolus multiple dosing?
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
What is the time to reach steady state?
3.3 half lives (only depends on the half life of the drug)
What is average concentration (Css,ave)?
the concentration that gives AUCss when maintained for tau
The same amount of dose administered per unit time will lead to what Css,ave?
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)
What is the difference between the average concentration equation for IV bolus and oral dosing?
oral dosing equation has bioavailability in the numerator of the equation that the IV bolus equation lacks
When you switch dosage regimen from 10 mg q12h to 10 mg q24h, what happens to fluctuation?
fluctuation increases
When you switch dosage regimen from 10 mg q12h to 10 mg q24h, what happens to average steady state concentration?
lower concentration
When you switch dosage regimen from 10 mg q12h to 10 mg q24h, what happens to time to reach a new steady state?
same since it is determined by half life (3.3 half lives)
When you switch dosage regimen from 10 mg q12h to 10 mg q24h, what happens to accumulation index?
accumulation index decreases (since tau increases, fluctuation increases, accumulation index decreases)
When you switch dosage regimen from 10 mg q12h to 20 mg q24h, what happens to fluctuation?
fluctuation increases (since tau increases)
When you switch dosage regimen from 10 mg q12h to 20 mg q24h, what happens to average steady state concentration?
same concentration (equation is dose/tau / CL)
When you switch dosage regimen from 10 mg q12h to 20 mg q24h, what happens to time to reach a new steady state?
the same since it is determined by 3.3 half lives
When you switch dosage regimen from 10 mg q12h to 20 mg q24h, what happens to accumulation index?
accumulation index decreases (since tau increases, fluctuation increases, accumulation index decreases)
What are the steps to dosing regimen design?
- know the target concentration range
- determine the maximum dosing interval (tau max) and round to a reasonable interval (ex. q6h, q8h, q12h, and once daily)
- determine maintenance dose (Dm) and choose Css,ave to fall in the middle of this range
- 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
- if necessary, determine loading dose (Dl)
What is the purpose of the loading dose?
loading dose is the first dose given to the patient and gives high enough concentration for the next doses (aka maintenance dose)
