| Summary: | 碩士 === 元智大學 === 化學工程研究所 === 87 === The swelling and drug permeation properties of the ammonio methacrylate copolymer membranes were studied. The pH values,
ionic strength, charged properties of drugs, plasticizer content in the polymer, and the ammonio group content in the membranes were
varied to study the their effects on the transport properties of drugs. Ambroxol and propranolol HCl were chosen as models for cation
drugs, acetylsalicylic acid (aspirin) as a model for anion drugs, and lactose for neutral compounds. The degree of swelling of the
membranes decreases as the ionic strength of the solution increases but it is irrelevant to the pH of the solution. Adding dibutyl
phthalate (DBP) as a plasticizer in the membranes may reduce the swelling of the membranes. The degree of dissociation of ionic
drugs in the pH buffered solution showed great influence on the degree of swelling of the membranes. There is a burst instead of
time-lag in all the drug permeation experiments because the initial permeation through the swollen membranes is very fast. The electric
repulsion or interaction occurs thereafter and the permeation rate for both anionic and cationic drugs is swelling controlled. Cationic
drugs achieve a pseudo-steady state after the initial burst and perform a two-stage permeation. The permeation rate in the second stage
is considerably slow due to the Donnan exclusion effect. Anionic drugs can interact with the cationic groups in the membranes and an
ion-exchange reaction occurs. The permeation rate is reduced due to the ion-exchange reaction and results in the slow down after the
initial burst. When all the cationic sites are saturated with the anionic permeates, the permeation tends to achieve a pseudo-steady state
at a rate comparably to the magnitude of the initial burst permeation rate. A three-stage permeation is resulted for the anionic drugs.
The pseudo-steady state permeability is much higher for anionic than cationic drugs and increases as the ionic strength in the solution
decreases and the ammonio group content in the membrane increases. Decreasing the ionic strength in the solution and increasing the
ammonio group content also shortens the commencement time for each stage for drug permeation. The relative magnitude of
permeability or the commencement time for each stage can well correlate with the equilibrium degree of swelling of the membranes;
that is, higher degree of swelling results in higher permeability and shorter commencement time for each stage.
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