week01.2.biopharm
Download
Report
Transcript week01.2.biopharm
Pharmacokinetics
objective is to describe time vs plasma
concentration profile of a drug
CHEE 440
evaluate performance of different dosage forms
adjust dosage regimens
ADME processes modeled by viewing body
as a series of interconnected compartments
1
CHEE 440
2
open one-compartment model
process of distribution to each compartment is much
faster than absorption into blood and elimination
drug concentration everywhere in the compartment is
equal (CSTR)
elimination processes are pseudo-1st order
Vd
ka
D
CHEE 440
Cp
DB
kel
Du
Dm
3
IV injection
dDB
k el D B
mass balance :
dt
Cp Cop exp k elt
log Cp
time, t
CHEE 440
4
Extravascular
tablets, capsules, transdermal...
most drugs absorbed by simple diffusion
DA
DB
DE
ka
k el
DoA k a
CP
exp kel t exp ka t
Vd ka k el
CHEE 440
5
Continuous infusion
k0
CP
1 exp k el t
Vd k el
Cp
time
CHEE 440
6
biological half-life
time required to reduce amount of drug in body
to 1/2 original dose
0.693
t1
2
k el
used to determine
fluctuation of plasma concentration between doses
persistence of drug in system once drug
administration ceases
CHEE 440
7
Dosing Schedule
MTC
Cp
MEC
time after administration
CHEE 440
8