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Surfactants Flashcards

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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
In the HLB classification system, what is range 3-6?
Water in oil emulsifying agent
26
In the HLB classification system, what is range 7-9?
Wetting / spreading agent
27
In the HLB classification system, what is range 8-16?
Oil in water emulsifying agent
28
In the HLB classification system, what is range 13-15?
Detergent
29
In the HLB classification system, what is range 15-18?
Solubilizing agent
30
At the surface of a liquid, molecules are....?
Not completely surround by other molecules
31
What is the result of the molecule at the surface of a liquid?
Net inward force of attraction which tends to form a sphere
32
Contraction of molecules near the surface of liquids are _______ which is accompanied by a ____ in free energy
Spontaneous Decrease
33
How does the shape of a liquid get its shape using surface tension
Assumes the shape having the least surface area
34
When an amphiphilic molecules touches water, what happens to surface tension?
Gets reduced
35
What is a good wettablity angle?
<60 degrees
36
What is a poor wettablilty angle?
>90 degrees
37
What is a total wettabliity angle?
0 degrees
38
What is wettability?
Extent to which a solid will physically interact with a liquid
39
When are Michelles formed?
Surface tension decreaes with increasing surfactant until critical michelle concentration is reached
40
Michelles are formed spontaneously / non-spontaneously
Spontaneously
41
What forms the core of Micelles?
Hydrophobic chains
42
What forms the shield of Micelles?
Hydrophilic groups
43
To form michelles, how would you decrease surface tension?
Add surfactants
44
For micellar systems at normal temperature, what is the most important in determining free energy change?
Entropy
45
What constitutes most of the delta G of micellar systems?
T * delta S
46
A drop in surface tension in micellar system is due to what?
Hydrophobic groups withdrawing from aqueous phase
47
The shape of the micellar system is affected by what?
1. Hydrophobic region | 2. Steric interactions
48
An increase in hydrophobic chain length _______ CMC
decrease
49
An increase in hydrophobic chain length ______ micellar size
increases
50
In general, ______ surfactants have lower CMC values and form larger micelles than its _____ counterparts
Nonionic Ionic
51
Phospholipids contain ______ and ______
Phosphate head and two fatty lipid tails
52
What to phospholipids and other surfactants with two hydrophobic chains tend to form?
Lamellar phase
53
When lamellar phases are equilibrated with excess water, these phases my form vesicles to do what on drugs? What purpose does it bring?
Entrap them Drug carriers/delivery systems
54
Unlike micelles, liposomes forming spherical vesicles is / is not spontanteous
is not
55
How do liposomes arrange themselves (assuming energy is added)?
Bilayer vesicle (alternates with aqueous compartments)
56
What three systems to liposomes use to form its vesicles?
1. Sonification 2. Homogenization 3. Ultrasonication
57
Liposomes are able to carry _______ + _______
Water-soluble and lipophilic moieties
58
Liposomes are classified by ____ and number of _____
Size Lamallae
59
Micelle vs liposome, which is multilayered?
Liposome
60
Micelle vs liposome, which can entrap and deliver both hydrophobic and hydrophilic materials?
Liposome
61
Micelle vs liposome, which required energy input?
Liposome
62
Micelle vs liposome, which is single-layered?
Micelle
63
Micelle vs liposome, which just has a hydrophobic layer?
Micelle
64
Micelle vs liposome, which can only entrap and deliver mostly hydrophobic materials?
Micelle
65
Micelle vs liposome, which is formed spontaneously?
Micelle
66
What are the three biggest issues with using liposomes for drug delivery?
1. Stability 2. Clearance rate 3. Distribution
67
When liposomes are administered IM or subQ, where does it enter? Why is it good?
Lymphatic system Good opportunity for vaccine delivery
68
What do liposomes provide in terms of targeting sites?
Passive targeting by reacting with antibodies (that will be phagocytized)
69
Cationic and anionic _____ onto bacteria surface which results in _____ and ultimately bacterial ____
Absorb leakiness death
70
Nonionic often (aid/inhibit) bacterial growth due to providing (insert nutrient) that is metabolized by microbes
aid fatty acids
71
Primary reason for micelle formation is reaching a ....?
minimum free energy state

Pharmaceutics (30 decks)

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