Exam 4 chapter 9 Flashcards
The 2 parameters that can be adjusted in developing a dosage regimen
- The size of the dose Do
- The frequency of administration, the dosage interval weird t
Accumulation as a function of dosing interval
Dosing rate is different time to reach ss is the same
For multiple dose regimens (For repetitive oral doses - the time required to reach steady-state: administered by any route):
accumulation will occur if all drug from 1st dose is not eliminated prior to the 2nd dose
elimination rate constant and absorption rate constant (accumulation rate)
A single large dose results in a large Cpo but low or zero levels prior to next dose—>
Relationship between T interval and T1/2
- poor continous coverage
- t >> T1/2
More frequent but divided dosing?
t is approaching T1/2 Cpo decreases but continuos coverage increases
When t __T1/2 Cpmax/Cpo becomes?
This is ____?
t<<t1>
<p>Cpmax becomes large</p>
<p>Accumulation occurs </p>
</t1>
Calculations for Loading dose DL
R = accumulation factor
Maximum concentration at SS
/
Maximum Concentration after 1st dose
Cave equation
Loading dose
When Ka > K ?
When the absorption rate constant is substantially larger then the elimination constant?
If the t interval is equal to the elimination T1/2?
Then the loading dose should be?
2 x the maintenance dose
Principle of superposition.
Early doses do not effect the pharmocokinetics of subsequent doses.
R value
= Drug accumulation
or
1/(1-e^-kt)
Where t is the interval this shows that accumulation is dependent on the elimination rate constant
Time to reach steady state
For a drug given in repetitive oral doses, the time required to reach steady state is dependent on the elimination half-life of the drug and is independent of the size of the dose, the length of the dosing interval, and the number of doses.
Average steady state concentration
AUC (for a dosing period)/ time interval at ss
