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MD8 Diffusion as an underlying principle of drug release

Mer Scott 9 questions

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  1. 1Diffusion is the [blank_start]random[blank_end] motion of the molecules from an area of [blank_start]high[blank_end] concentration (activity) to an area of [blank_start]low[blank_end] concentration. It is a [blank_start]passive[blank_end] process.
    1. Arandom
    2. Bhigh
    3. Clow
    4. Dpassive
  2. 2The flux (J) is the amount of material that crosses a unit area of a membrane over time, and so it is a rate. Choose the correct equation for flux.
    1. AJ = dM/A.dt
    2. BJ = dM.A/dt
    3. CJ = dM.dt/A
  3. 3- Drug related factors influencing diffusion:
    Molecular [blank_start]size and shape[blank_end], degree of [blank_start]ionisation[blank_end], [blank_start]pka[blank_end]

    - Medium related factors influencing diffusion:
    [blank_start]lipophilicity, thickness, viscosity[blank_end], pH

    - System related factors influencing diffusion:
    [blank_start]Temperature change[blank_end] which affects viscosity
    1. Asize and shape
    2. Bionisation
    3. Cpka
    4. Dlipophilicity, thickness, viscosity
    5. ETemperature change
  4. 4The flux (J) is proportional to the difference in concentrations across the unit area. As an equation that is [blank_start]Fick's first law[blank_end]:
    J = [blank_start]-D[blank_end] * [blank_start](dC/dx)[blank_end]
    Where J is flux and always [blank_start]positive[blank_end], D is the diffusion coefficient ([blank_start]negative[blank_end] because concentration is high to low), C is the [blank_start]difference in concentrations[blank_end], and x is the [blank_start]diffusional distance[blank_end].
    Diffusion coefficient , D (cm2/s) is a measure of the ease of movement of molecules across the region. It may change with concentration, temperature, pressure, solvent properties, and solute properties
    1. AFick's first law
    2. B-D
    3. C(dC/dx)
    4. Dpositive
    5. Enegative
    6. Fdifference in concentrations
    7. Gdiffusional distance
  5. 5Fick's 2nd law of diffusion examines the [blank_start]rate[blank_end] of change of diffusant [blank_start]concentration[blank_end] at a [blank_start]point[blank_end] in the system (rather than mass transfer across a barrier). The [blank_start]change in concentration[blank_end] with time at/in any particular region is proportional to the [blank_start]change in the concentration gradient[blank_end] at that point in the system.
    1. Arate
    2. Bconcentration
    3. Cpoint
    4. Dchange in the concentration gradient
    5. Echange in concentration
  6. 6[blank_start]Fick's first law of diffusion[blank_end]
    - describes the flow of a material through a unit crosssection of a barrier in unit time
    [blank_start]Fick's second law of diffusion[blank_end]
    - describes the change in concentration at a particular point in the system with time
    1. AFick's first law of diffusion
    2. BFick's second law of diffusion
  7. 7Choose the incorrect statement.
    1. AA drug permeates by diffusion through the membrane.
    2. BA drug present in the donor compartment is separated from a receptor compartment by a polymer membrane.
    3. CA drug partitions into a membrane.
    4. DThe receptor compartment and donor compartments are both sinks.
  8. 8The concentration on the donor side but inside the membrane is C1 while the concentration inside the membrane by the side side is C2. C1 and C2 [blank_start]can’t be measured[blank_end] (they are inside the membrane) but are related to the donor (Cd) and receptor (Cr) concentrations by the [blank_start]partition coefficient, K[blank_end].
    C1 = [blank_start]K*Cd[blank_end] and C2 = [blank_start]K*Cr[blank_end]
    1. Acan’t be measured
    2. Bpartition coefficient, K
    3. CK*Cd
    4. DK*Cr
  9. 9For sink conditions [blank_start]Cr = O[blank_end], so da/dt = [blank_start](D.K.A.Cd) / h[blank_end].
    D.K/h is a constant known as the [blank_start]partition coefficient[blank_end], P.
    Therefore, da/dt = [blank_start]P.A.Cd[blank_end].
    P has units of velocity (cm s-1) and is typically equal to [blank_start]10-5 – 10-7[blank_end] cms-1. P is useful because it is often [blank_start]hard to independently measure[blank_end] the partition co-efficient (K) and the diffusion co-efficient (D).
    1. ACr = O
    2. B(D.K.A.Cd) / h
    3. Cpartition coefficient
    4. DP.A.Cd
    5. E10-5 – 10-7
    6. Fhard to independently measure

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Description
PHCY211 (Medicines) Quiz on MD8 Diffusion as an underlying principle of drug release, created by Mer Scott on 13/05/2018.
Author
Mer Scott
Language
English
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