Pharmacokinetics Formulas Flashcards
What is the velocity equation for elimination kinetics
Velocity=(Vmax*S)/(Km+S)
When will you obtain zero order elimination kinetics
when the velocity equals the max. Here S is at high concentration so the Km is too small and is neglected and then the S cancels out
what about first order
when the velocity=Vmax*S/km
what is the equation for Apparent volume of Distribution (avd)
doses/Co or the concentration in blood
the volume of blood or aVd that appears to be cleared of drug per unit time.
Cl=ke*aVd
what is the slope of ln transformed blood decay curve
ke
what is the time for the half life equal to
t1/2: 0.693/ke
what two things are equal at steady state during drug infusion
the rate of elimination=rate of administration
what is the infusion rate equal to
Cl*Css
what is the formula for the loading dose
aVd*Css
Maintenance dose Rate is equal to
the infusion rate
if the drug is given orally what is the rate of elimination equal to
ClCss=(DF)/T
D=Dose
F= is the fraction absorbed
T= is the dosage interval
what is the loading dose if the drug is given orally
Loading dose=(aVd*Css)/F
