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Pharmaceutics > Surfactants > Flashcards

Surfactants Flashcards

1
Q

What are surfactants?

A

Surface active agents with two distinct regions in their chemical structure (polar head and nonpolar tail)

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2
Q

How are surfactants generally classified?

A

According to its hydrophilic group

EX: anionic, cationic, zwitterionic or non-ionic

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3
Q

What is the most widely used surfactant class?

A

Anionic

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4
Q

What are the most common encountered anionic surfactants?

A

Carboxylate, sulfate, sulonate, or phosphate polar groups

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5
Q

Counter ions help with what?

A

Solubilty

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6
Q

Sodium and potassium counter ions are for ____ solubility

A

water

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7
Q

Calcium or magnesium counter ions are for ____ solbility

A

oil

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8
Q

In most cationic surfactants, charge is found on a _____ atom

A

nitrogen

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9
Q

Cationic surfactants function in ______ state

A

protanated

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10
Q

How does quaternary ammonium (cationic surfactant) compound work?

A

Retains charge over the entire pH range

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11
Q

How does amine compounds (cationic surfactant) work?

A

Charged at lower pH

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12
Q

What are zwitterionic compounds?

A

Molecules that contain both positive and negative charge upon full ionization

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13
Q

How is the positive charge carried in zwitterionic compounds?

A

Ammonium group

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14
Q

How is the negative charge carried in zwitterionic compounds?

A

Carboxylate group

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15
Q

If the ammonium group in zwitterionic compounds is quaternary, how will the molecule exist?

A

Zwitterion over a wide pH range since the quaternary ammonium group will be permanently charged

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16
Q

If the amine group in zwitterionic compound is NOT quaternary, how will the molecule exist

A

Goes from cationic to zwitterionic and finally to anionic as pH is increased

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17
Q

If the amine group in zwitterionic compound is NOT quaternary, the molecules goes from _____ to zwitterionic to ______ as pH is ________

A

Cationic
anionic
increased

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18
Q

At the isoelectric point (in zwitterionic compounds) both groups are fully ionized and behave like what surfactant?

A

Nonionic

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19
Q

Why are nonionic surfactants used for?

A

Good compatibility, stable, low toxicity

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20
Q

In the HLB classification system, the higher the number, the more ______ the surfactant

A

hydrophilic

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21
Q

In the HLB classification system, the ______ the number, the more hydrophilic the surfactant

A

higher

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22
Q

In the HLB classification system, what does HLB stand for?

A

Hydrophilic-lipophilic balance

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23
Q

In the HLB classification system, what is the range?

A

0-20

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24
Q

In the HLB classification system, what is range 2-3?

A

Antifoaming agent

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25
Q

In the HLB classification system, what is range 3-6?

A

Water in oil emulsifying agent

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26
Q

In the HLB classification system, what is range 7-9?

A

Wetting / spreading agent

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27
Q

In the HLB classification system, what is range 8-16?

A

Oil in water emulsifying agent

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28
Q

In the HLB classification system, what is range 13-15?

A

Detergent

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29
Q

In the HLB classification system, what is range 15-18?

A

Solubilizing agent

30
Q

At the surface of a liquid, molecules are….?

A

Not completely surround by other molecules

31
Q

What is the result of the molecule at the surface of a liquid?

A

Net inward force of attraction which tends to form a sphere

32
Q

Contraction of molecules near the surface of liquids are _______ which is accompanied by a ____ in free energy

A

Spontaneous

Decrease

33
Q

How does the shape of a liquid get its shape using surface tension

A

Assumes the shape having the least surface area

34
Q

When an amphiphilic molecules touches water, what happens to surface tension?

A

Gets reduced

35
Q

What is a good wettablity angle?

A

<60 degrees

36
Q

What is a poor wettablilty angle?

A

> 90 degrees

37
Q

What is a total wettabliity angle?

A

0 degrees

38
Q

What is wettability?

A

Extent to which a solid will physically interact with a liquid

39
Q

When are Michelles formed?

A

Surface tension decreaes with increasing surfactant until critical michelle concentration is reached

40
Q

Michelles are formed spontaneously / non-spontaneously

A

Spontaneously

41
Q

What forms the core of Micelles?

A

Hydrophobic chains

42
Q

What forms the shield of Micelles?

A

Hydrophilic groups

43
Q

To form michelles, how would you decrease surface tension?

A

Add surfactants

44
Q

For micellar systems at normal temperature, what is the most important in determining free energy change?

A

Entropy

45
Q

What constitutes most of the delta G of micellar systems?

A

T * delta S

46
Q

A drop in surface tension in micellar system is due to what?

A

Hydrophobic groups withdrawing from aqueous phase

47
Q

The shape of the micellar system is affected by what?

A
  1. Hydrophobic region

2. Steric interactions

48
Q

An increase in hydrophobic chain length _______ CMC

A

decrease

49
Q

An increase in hydrophobic chain length ______ micellar size

A

increases

50
Q

In general, ______ surfactants have lower CMC values and form larger micelles than its _____ counterparts

A

Nonionic

Ionic

51
Q

Phospholipids contain ______ and ______

A

Phosphate head and two fatty lipid tails

52
Q

What to phospholipids and other surfactants with two hydrophobic chains tend to form?

A

Lamellar phase

53
Q

When lamellar phases are equilibrated with excess water, these phases my form vesicles to do what on drugs? What purpose does it bring?

A

Entrap them

Drug carriers/delivery systems

54
Q

Unlike micelles, liposomes forming spherical vesicles is / is not spontanteous

A

is not

55
Q

How do liposomes arrange themselves (assuming energy is added)?

A

Bilayer vesicle (alternates with aqueous compartments)

56
Q

What three systems to liposomes use to form its vesicles?

A
  1. Sonification
  2. Homogenization
  3. Ultrasonication
57
Q

Liposomes are able to carry _______ + _______

A

Water-soluble and lipophilic moieties

58
Q

Liposomes are classified by ____ and number of _____

A

Size

Lamallae

59
Q

Micelle vs liposome, which is multilayered?

A

Liposome

60
Q

Micelle vs liposome, which can entrap and deliver both hydrophobic and hydrophilic materials?

A

Liposome

61
Q

Micelle vs liposome, which required energy input?

A

Liposome

62
Q

Micelle vs liposome, which is single-layered?

A

Micelle

63
Q

Micelle vs liposome, which just has a hydrophobic layer?

A

Micelle

64
Q

Micelle vs liposome, which can only entrap and deliver mostly hydrophobic materials?

A

Micelle

65
Q

Micelle vs liposome, which is formed spontaneously?

A

Micelle

66
Q

What are the three biggest issues with using liposomes for drug delivery?

A
  1. Stability
  2. Clearance rate
  3. Distribution
67
Q

When liposomes are administered IM or subQ, where does it enter? Why is it good?

A

Lymphatic system

Good opportunity for vaccine delivery

68
Q

What do liposomes provide in terms of targeting sites?

A

Passive targeting by reacting with antibodies (that will be phagocytized)

69
Q

Cationic and anionic _____ onto bacteria surface which results in _____ and ultimately bacterial ____

A

Absorb

leakiness

death

70
Q

Nonionic often (aid/inhibit) bacterial growth due to providing (insert nutrient) that is metabolized by microbes

A

aid

fatty acids

71
Q

Primary reason for micelle formation is reaching a ….?

A

minimum free energy state

Pharmaceutics (30 decks)

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