Pharmacokinetics 5-6 Flashcards
1
Q
Why are pharmacokinetics important?
A
- determine drug behavior
- safe & effective dose in animal systems
- optimization of therapeutic conc.
2
Q
Bioequivalence
A
Comparing new drug w/ known version
3
Q
Dosage regimen
A
Absorption + distribution + elimination
4
Q
AUC (area under curve)
A
- total amt. of drug that comes into systemic circulation
- helps evaluate bioavailability of drugs
- represents extent of absorption
- expressed as product of drug conc. and time
5
Q
Trapezoidal rule
A
- divide plasma conc.-time profile into several trapezoids
- add the AUCs of all the trapezoids
6
Q
Volume of distribution (Vd)
A
- Vd= Dose/Plasma conc
- higher tissue dist.->more lipid soluble; mainly tissues
- lower tissue dist. -> more H2O soluble; plasma mainly, maybe tissue
- dose must be given IV
7
Q
Protein bound Vd
A
- plasma only
- 5% body wt.
8
Q
H2O soluble Vd
A
- extracellular fluid
- 20-30% body wt.
9
Q
Lipid soluble Vd
A
- plasma (mostly), ECF and ICF, or Total body water
- 60-70% body wt.
10
Q
Elimination kinetics
A
- k= elimination rate constant
- 1st order kinetics more common than zero order
- determines dosage; dose interval; duration in body
11
Q
First order kinetics
A
- most common
- Fixed fraction of drug processed
- constant 1/2 life
- usually eliminated in 5 half lives
12
Q
Zero order kinetics
A
- fixed amt. of drug processed per time
- not usually common
- 1/2 life dependent on dose given
13
Q
Clearance rate
A
Cl= (dose/AUC) * (vol/time)
14
Q
Half life
A
- t 1/2= 0.693* Vd/Cl
- shorter= rapid elimination
- good way to determine dosing intervals
- entero-hepatic circulation and plasma protein binding increase 1/2 life
- may increase in renal or hepatic dysfunct.
15
Q
Dose
A
Amt of drug administered to produce response
- Dose= Cmax * Vd
