Multiple Dose Flashcards
What does dosage regimen depend on?
- Strength
- Frequency of drug administration
Plasma drug concentration predictions are based on…
- Pharmacokinetic parameters obtained from single dose
- Strength
- Dosage interval (Tau)
What is the principle of superposition?
Subsequent doses don’t interfere w/ kinetics of early doses
When can’t you use the principle of superposition?
- If there is interaction at transport level or enzyme level
- If drug affects cardiac output
Window between Cmax and Cmin will be greater for a _____ dosing interval
Longer
What is accumulation half life? What determines it?
- Time to reach 1/2 Css
- Determined by elimination half life, NOT absorption rate constant (ka)
What happens to Cmax, Cmin, and C average when dosage interval increases?
- Cmax decreases
- C average is unchanged
- Cmin decreases
What does f mean?
Fraction of dose remaining in the body
What is n at steady state?
Infinity, so would use a formula w/o n
What must be calculated if you want to know max concentration at steady state?
tp (time to reach maximum concentration)
What is the dose ratio (DL/D0) when tau (dosage interval) = t1/2?
Ratio = about 2
What are some advantages to using single dose data to determine bioequivalence?
- Patient acts as own control
- Cmin is maintained
- Assay is more accurate
What are some disadvantages to using single dose data to determine bioequivalence?
- Takes longer time to complete study
- Need more samples
What does multiple dose take into account?
IV and oral
What is R for multiple dose? What does it depend and not depend on?
- R = index of drug accumulation
- Dependent on dosing interval and rate constant
- Independent of dose
