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Kinetics > E1 L2: Drug Distribution > Flashcards

E1 L2: Drug Distribution Flashcards

1
Q

Passive diffusion properties

A

Drug passes down concentration gradient
Not saturated
Most common

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2
Q

Transcellular junctions

A

Cross lipid bilayer (go through)

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3
Q

Paracellular diffusion

A

Go between (for hydrophilic small molecules)

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4
Q

Facilitated diffusion

A

Down concentration gradient
Via carriers
Saturable
E.g. Organic anion transporting polypeptides (OATP)

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5
Q

Active transport

A

Against concentration gradient
Via transporter
Uses ATP (energy)
Saturable
Ex. P-glycoprotein

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6
Q

Passive diffusion graphed

A

Increases linearly with concentration

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7
Q

Carrier mediated transport graphed

A

Curved - too much drug in system = saturation (saturated at high drug concentrations)

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8
Q

Passive diffusion:
Involvement of a protein channel or transporter?
Saturable?
Direction?
ATP Use?

A

No
No
High to low conc
No

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9
Q

Passive FACILITATED diffusion:
Involvement of a protein channel or transporter?
Saturable?
Direction?
ATP Use?

A

Yes
Yes
High to low
No

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10
Q

Active Transport:
Involvement of a protein channel or transporter?
Saturable?
Direction?
ATP Use?

A

Yes
Yes
Low to high
Yes

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11
Q

Factors determining diffusion

A

Molecular size - poor permeability for large molecules
Lipophilicity - poor permeability for hydrophilic molecules

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12
Q

Indicator of compound lipophilicity
The larger, the more lipophilic (hydrophobic)

A

LogP

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13
Q

Best permeability has..

A

Small MW
Large LogP

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14
Q

Factors determining diffusion

A

Molecular size
Lipophilixty
Charge

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15
Q

Q: T/F: Salicylic acid will exhibit better crossing through the lipid bilayer at higher pH (ie. in basic condition)

A

False - higher pH = ionized= worse permeability

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16
Q

Perfusion rate limited

A

Only limiting factor- rate of blood flow

17
Q

Permeability rate limited

A

Do not cross membrane readily

18
Q

Perfusion rate limitation: hydrophobic or hydrophilic?

A

Hydrophobic (rate of blood flow)

19
Q

Permeability rate limitation: hydrophobic or hydrophilic?

A

Hydrophilic (does not readily cross membrane)

20
Q

Perfusion vs. Permeability rate limited graphed

A

Perfusion: High concentration (more lipophilic)
Permeability (low line)

21
Q

Q: which of the following would have a faster propofol distribution (nonpolar lipophilic - LOG P = 3.79)
Brain: perfus rate: 0.5
Muscle: Perfus rate 0.025

A

Brain - Compound is perfusion rate limited
Small compound that distributes perfusion rate limited

22
Q

Major drug binding plasma proteins

A

ALBUMIN
a1-acid glycoprotein
Lipoproteins

23
Q

Most abundant plasma protein
Produced in the liver
Binds FFA, hormones, and weakly acidic (anionic) drugs
Main function - maintain oncotic pressure of blood
Serum levels decreased in liver and kidneys

A

Albumin

24
Q

AKA orosomucoid
Produced in liver
Binds primarily weak basic (cationic) drugs such as tertiary and quaternary amines
Serum levels increase during acute phase reaction, e.g. inflammation and burns
Serum levels are decreased in liver and kidney diseases

A

a1-Acid glycoprotein (AAG)

25
Q

Lipophyllic protein and/or a complex of proteins and lipids
Includes HDL and LDL
Binds hydrophobic drugs
Altered in some disease states, including heart disease

A

Lipoproteins

26
Q

Free drug hypothesis:

A

Only free drug exists capillaries to reach extravascular sites of action
Only free (unbound) drug crosses cell membrane via diffusion
Only free (unbound) drug binds to transporters

27
Q

T/F: Plasma protein binding of drugs is reversible

A

True

28
Q

Plasma makes up how much of the total blood volume?

A

50%

29
Q

Coagulated blood that settles at the bottom of the tube

A

Serum

30
Q

Serum is devoid of

A

Blood cells
Fibrin
Clotting factors

31
Q

Serum contains

A

Plasma proteins (like albumin)

32
Q

Unbound fraction

A

Free drug concentration/Total concentration

33
Q

Determinants of Vd

A

V = Vp + VTW * fu/Fut

34
Q

Q: T/f: Ionized compounds show poorer membrane permeability than unionized compound

A

True

35
Q

Q: T/F: Lipophilic compounds tend to show greater membrane permeability

A

True

36
Q

Q: T/F: Lipophilic compounds tend to show permeability rate-limited distribution

A

False (lipophilic=diffusion rate limited)

37
Q

Q: T/F: Decreased plasma protein binding of high protein bound drugs will likely increase Vd

A

True

38
Q

Q: T/F: Vd is expected to be small for a drug that exhibits strong binding to tissue components

A

False - (goes up)

Kinetics (20 decks)

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