Pharmacokinetics III Flashcards
Understand which pharmacokinetic parameters are attained from log concentration and/or arithmetic concentration versus time plots
Log concentration plots gives us * Absorption * Distrbution * Elimination * Half lives Arithmetic plots gives us * Total drug concentration over time = AUC * Clearence * Bioavailibility
Understand first-order and zero-order kinetic processes.What do their arithmetic and log plots look like?
Zero order kinetic processes remain constant over time, do not depend on the concentration of reactants or products, rate of reaction = constant. Log plots of zero order kinetics reactions gives a curved line.For first order kinetics processes, rate of reaction is proportional to the concentration of reactant, rate of reaction = k[C]
Know the difference between dose-dependent and dose-independent pharmacokinetics
Drugs that follow zero order kinetics have dose dependents pharmacokinetics whereas drugs that follow first order or second order kinetics have dose independent (1st or 2nd order) pharmacokinetics.
Know the relationship between half-life and elimination rate constant
t1/2 = 0.693 / KelwhereKelis elimination rate constant given byKel= CL / VD
What is the realtionship of clearence with plasma concentration and rate of elimination?
How is clearence related to VD and t1/2
Cl = VD x KelCl = VD x 0.693/ t1/2
What are the equations for renal clearence?
Know the equation for calculating the amount of drug in the body
How long does it take for a drug to reach steady state concentration in the human body?What can be done to fasten this process?
It takes about 4 to 5 half lives for a drug to reach state state concentration.A loading dose can be given which will be higher than the normal dose in order to reach steady state concentration faster.
Understand the parameters that determine if a drug follows one-compartment or multicompartment kinetics
One compartment kinetics occur when drug concentration in all tissues is in rapid equilibrium with drug in plasma.Multicompartmentkinetics occur when drug concentration in the plasma slowly equilibrates into tissues with significant mass (ex. fat).For drug to follow multicompartment kinetics Kab, K1, K2 and Kel have to vary significantly.
Know the difference between bioavailability and bioequivalence
Bioavailibility is the amount of (unbound) drug that is present in the plasma.For 2 drugs to be bioequivalent their Tmax, Cmax and AUC have to be the same.
Know the equations and parameters that affect concentration at steady-state when a drug is given by repetitive dosing
Know how to calculate loading dose and maintenance dose for both intermittent and continuous drug exposures
LD = Css x VD / FWhere F is bioavailibility and Vd is volume of distribution.D/T = Css x Clwhere D is dose, T is time and Cl is clearence
