Lecture 4
CHE 618
Membrane transport
Role of pH
Solvents
Metabolism and transport
)( recsource CCPJ Permeability, m/s
Flux
Fick’s Law
Concentration (molarity, …)
Diffusion-limited mechanism:Diffusion-limited mechanism:
Jdiff = Dm/lm ([M]m,s)
[M]m,s = Kex[M]
Jdiff = Dm/lm• Kex[M]
P = (DmKex)/lm
permeability
Water Membrane Water
layerBoundary Boundary
layer
ls
lm
l r
Js = Ds/ls ([M]s - [M]m,s) Jin = k1[M]m,s - k-1[M]m,s
Jdiff = Dm/lm ([M]m,s - [M]m,r)
Jout = -k1[M]m,r + k-1[M]m,r Jr = Dr/lr ([M]m,r - [M],r)
DMSO
b.p. 189 C
Poly(ethylene oxide)
Solvent-facilitated transport
Carrier – facilitated transport
Active transort
Ion channels and ion pumps
First-order process
DRUG half-life(hours)
Penicillin 0.5Insulin 0.7Aspirin 6Tetracycline 9Sulfadimethoxine 30Vitamin D 40
First-order elimination kinetics
log C
time
log C
time
One-compartment kinetics Two-compartment kinetics
[B]
time
First order consecutive process
¼ mg /mL cocaine
0.05-0.10 mg/mL cocaine
Cocaethylene
H
Methylecgonine
benzoylecgonine
Ecgonine
3-hydroxy-8-methyl-8-azabicyclo [3.2.1]octane-2-carboxylic acid
Cocaine metabolic profile. BE-benzoylecgonine, EME-ecgonine methyl ester,CE- cocethylene
6-MAM