Term
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Definition
| Spontaneous, random transfer of diffusants across a diffusional barrier from a region of higher concentration to a region of lower concentration |
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Term
| What is another term for the random motions of diffusion? |
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Definition
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Term
| List three reasons diffusion is relevant to pharmacy |
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Definition
1. Drug absorption/elimination
2. Manufacturing- lysophilization, leaching
3. Drug release |
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Term
Define flux
Give an example for units flux would be in |
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Definition
Mass transfer per unit time per unit area
g/(cm*sec) |
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Term
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Definition
Mass going in= mass going out
(Still dynamic, does not necessarily mean equality on either side)
dC/dT is unchanged |
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Term
| What is the rate of diffusion directly proportional to? |
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Definition
| Surface area and concentration gradient |
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Term
| What is the rate of diffusion inversely proportional to? |
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Definition
| Thickness of membrane/barrier |
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Term
| In Fick's first law, what is D? |
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Definition
D= diffusion coefficient
(changes based on temp/pressure) |
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Term
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Definition
dM/dt = D* S* dC/dx
D=coefficient
S=surface area
dC= concentration gradient
dx= thickness of membrane |
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Term
| When graphing concentration vs distance, what does the slope represent? |
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Definition
dC/dx
Which can than be plugged into Fick's law |
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Term
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Definition
dC/dt=D*d2C/dx2
Describe changes in conversation verses time |
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Term
| Give the equation for the amount of material diffusing |
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Definition
M=S*P*t*Cd
(given to us on exam)
S=surface area
P=permeability, given
t=time
Cd=[] in donor compartment |
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