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Pharm 2 > Test 1-Mass transfer > Flashcards

Test 1-Mass transfer Flashcards

1
Q

What is mass transfer (definition)?

A

A net movement of mass from one location to another in response to applied driving forces

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2
Q

When and where in the human body does mass transfer happen?

A

Occurs across different types of cell membranes and under different physiological conditions

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3
Q

What studies is mass transfer important for?

A

Dosage form design
ADME

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4
Q

What does diffusion of a drug through biological membrane involve?

A

Diffusion
Partitioning
Permeation

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5
Q

What is the diffusion step?

A

The drug’s diffusion through the aqueous medium that bathes the membrane

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6
Q

What is the partitioning step?

A

Passage of the drug molecules form the aqueous medium of the GI fluids into the lipid bilayer of the membrane

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7
Q

What is the permeation step?

A

Diffusion of the drug through the membrane

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8
Q

What is drug permeation?

A

Drug transfer - molecular diffusion of the drug through relatively non porous media

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9
Q

What does drug permeation depend on?

A

Drug partitioning
The structural nature of biological membrane
The nature of diffusion layer (GI content)

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10
Q

What is drug partitioning?

A

The ability of the drug to distribute in a mixture of aqueous and lipid system

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11
Q

How is drug partitioning across biological membrane measured?

A

By using a mixture of octanol (nonpolar) and water (polar) to get Kd and then Lop P which represents the drugs lipophilicity

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12
Q

What does lipophilicity affect?

A

Aqueous solubility (decreases with an increasing Log P)
Permability (increases with increase in Log P)

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13
Q

How do most therapeutic agents exist?

A

As either weakly acidic or basic in nature

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14
Q

What does aqueous solubility of a drug depend on?

A

pKa or the dissociation constant
pH of the solution

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15
Q

TF: The ionized states of a drug exhibit greater aqueous solubility than un ionized states

A

True because the ionized states are polar

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16
Q

What does pH of the surrounding fluid affect for the drug?

A

Solubility
Dissolution
Permeation

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17
Q

What kind of drugs are predominantly present in their un-ionized forms in the GI fluid in the stomach and upper part of the duodenum?

A

Weakly acidic drugs because of the lower pH which aids in their permeation in these areas

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18
Q

What kind of drugs are poorly absorbed in the stomach?

A

Weakly basic drugs
They exist largely in the ionized states at the GI pH

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19
Q

Why is the lipophilic nature of drugs important?

A

Because the biological membranes are lipid barriers

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20
Q

What is the most common process for the passage of drugs through biological membranes?

A

Passive diffusion

21
Q

What is passive diffusion?

A

When drugs diffuse across a cell membrane from a region of high concentration (GI fluid) to a region of low concentration (blood)

22
Q

What is diffusion rate directly proportional to?

A

The gradient

23
Q

TF: small particles pass the membranes much slower than large molecules

A

False
They diffuse faster

24
Q

What is passive diffusion of drugs governed by?

A

Fick’s law of diffusion

25
Q

Drug molecules bound to other structural materials do/dont participate in diffusion process?

A

Do not

26
Q

What happens in transcellular transport?

A

Drugs diffuse through the matrix or core of the membrane

27
Q

Transcellular transport is ______ across different tissue membranes.

A

Constant

28
Q

What does transcellular transport depend on?

A

Lipophilicity, polarity and molecular weight of drug molecule

29
Q

What happens during paracellular transport?

A

Drugs diffuse through the water filled gaps between adjacent cells

30
Q

Paracellular transport ____ from tissue to tissue.

A

Vary

31
Q

What does paracellular transport depend on?

A

Size of the junction and size of the drug molecules

32
Q

What polar compounds cross the biological membrane faster than non polar compounds?

A

Ones that have specialized carrier and transporters

33
Q

What is the best studied system of active transport?

A

ATPase proteins that are particularly important in maintaining concentration gradients of small ions in cells

34
Q

What are transporters?

A

Proteins that reside on biological membranes and serve to facilitate the passage of chemicals into or out of a cell

35
Q

What do transporters located on the intestinal membrane influence?

A

Drug absorption

36
Q

What do transporters on the hepatocyte influence?

A

Metabolism

37
Q

What do transporters on the renal tubular membrane influence?

A

Excretion

38
Q

What is MRP?

A

Multi-Drug Resistance Proteins

39
Q

What is BSEP?

A

Bile Salt export pump

40
Q

What are the two broad classes of transporters?

A

Influx (uptake) transporters
Efflux transporters

41
Q

What do influx transporters do?

A

Transport drugs into the tissue/cell

42
Q

What type of transporter is MRP?

A

Efflux

43
Q

What type of transporter is BSEP?

A

Efflux

44
Q

What do efflux transporters do?

A

Transport drug out of the tissue/cell

45
Q

What are OATPs and what type of transporters are they?

A

Organic anionic transport proteins
Influx

46
Q

What type of transporter is p-glycoprotein?

A

Efflux

47
Q

What is MDR1 and what type of transporter is it?

A

Multi drug resistance 1
Efflux

48
Q

What is BCRP and what type of transporter is it?

A

Breast cancer receptor proteins
Efflux

49
Q

What is pore transport?

A

The aqueous channels which exist in cell membranes to allow very small hydrophilic molecules such as urea, water and low molecular weight sugars to be transported into the cell

Pharm 2 (7 decks)

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