Page 27 - controlled drug delievery
P. 27
Cont. Diffusion controlled S.
1-A-Reservoir type
Fick’s diffusion law (for membrane diffusion):
dm = DAK (Ci - C0)
dt h
dm/dt = drug diffusion rate
D:NDoyifefsu-sWiohnitcnoneefyficeiqeunatt(iodne:pends on the drug molecular size)
A: Dosage form surfacdeca=rKeAa(.Cs-C)
K: Partition coefficientdt
CiT: hderulogwceornlcimenittroaftdiorunginsosliudbeiltihtyetsoybsteefmorm(muolasttelyd =inCasS)R/CR
C0s:ydstreumg choans cbeenetnraretipoonrtoeudttsoidbeet0h.1e-m1 memg/bmral ne.
h: Thickness of the membrane.
