Exam 2: Pharmacokinetics Flashcards
The mathematical description of the plasma concentration- time course
Pharmacokinetics
What are the 4 components of a dosage regimen?
- Dosage
- Route of admin
- Frequency
- Druation of admin
The optimum dosage regimin has what 3 qualities?
- Effective
- Non toxic
- W/O prolonged drug residues in tissues of food an.
The time to peak plasma conc.
Rate of absorption (tmax)
Measured by systemic bioavailablility (F%)
Extent of absorption
The fraction of the dose which reaches the systemic circ. intact
Systemic bioavailability
what is the one compartment model?
all tissues which the drug penetrates behaves as if they were in ready equilibrium with blood
What is the two compartment model?
drug moves in the body as if 2 commpartment
What is the most common compartment model?
2 compartment
Estimated by the distribution phase half time in the two compartment model
Rate of Distribution
Measured by the apparent volume of distribution (Vd)
Extent of distribution
The volume of fluid which would be required to contain the amount of the drug in the body if it were uniformly distributed, and the conc. in that fluid was equal to te conc. in the plasma
(Vd) Apparent volume of distribution
The amt. of drug in the body
Dose IV
What does it mean when a drug has a Vd <1L/kg
Drug has limited distribution (stays in plasma)
What does it mean when a drug has a Vd =1L/kg?
Drug has a wide distribution
What does it mean when a drug has a Vd> 1L/kg
Drug has a very wide distribution
How is elimination measured
half life or total body clearance
The time required for the body to eliminate one- half of the drug
half life (t1/2)
Elimination of most drugs follows what order kinetics
First
Elimination of a constant fraction per time of the drug
First order kinetics
Elimination = proportional to the conc. of drug
First order kinetics
First order kinetics is considered a ___ process
Linear
Constant amt. of drug is eliminated per unit time
Zero order kinetics
When does zero order kinetics occur?
when saturated
The plasma conc. of drug when the maintenance rate of drug admin. is qual to the rate of elimination
Steady- State plasma conc.
The rate of drug elimination from the body, by all routes, relative to the conc. of drug in plasma
Total body clearance (clB)
The volume of plasma cleared of the drug per unit time
Plasma clearance (CLp)
The fraction of the drug removed from the perfusing blood by an organ
Extraction ratio
