pharmacokinetics

what is drug transport

movement through membranes

what drugs penetrate the membrane

only unionised non polar drugs

what is the half life of a drug determined by

The elimination constant

how should small half life drugs be administered 

by IV drips so you don’t have to inject every few minutes 

what is another way can you view the rate of elimination 

Through fraction of dose remaining 

What is the equation for the fraction of dose remaining

Fraction of dose remaining = A(t)/dose = e^-kt

What is volume of distribution not equal to

Volume of blood

What is the equation of rate of elimination

CL x C(t)

How is the total amount of the drug eliminated assessed

by integrating the amounts of drug at each short time interval

dose = CL x AUC —> CL = dose/AUC

what is clearance 

the amount of blood clear from the drug per unit of time

what is clearance related to

the total elimination of all drug from the body irrespective of how it is eliminated 

what is the equation for volume of distribution

V = CL/k = dose/ k x AUC

how can the rate of elimination from the body be viewed

in terms of residence time indicating how long drug molecules stay in the body

what is the mean residence time

the average time molecules of a drug stay in the body

how is MRT obtained

by adding the number of residing molecules of the drug in the body over all times and dividing by the total number of molecules, the dose

what is the equation of MRT 

MRT = 1/Kelim

what are the 2 different compartment models

• one compartment (body) model

• two compartment model 

how is the drug distribution in the body approximated 

by compartments, which are kinetically defined

how can the oral absorption of drugs be well described by

by the first order kinetics (especially when given in solution)

what is the rate of absorption proportional to

the amount remaining to be absorbed

what is the equation for rate of change of drug in the body

rate of change of drug in the body = rate of absorption - rate of elimination 

what does absorption influence 

influences the time course of drug in the body 

what is the equation for the total amount eliminated

total amount eliminated = CL x AUC

what is bioavailability

the fraction of drug that reaches systemic circulation

what is the equation for bioavailability

F x dose = CL x AUC

what does slowing absorption delay

delays the attainment (tmax) and decreases (Cmax) of the peak plasma conc.