Exam 1 Flashcards
1
Q
what is benzoic acid
A
preservative
2
Q
what is citric acid
A
buffering agent or antioxidant
3
Q
what is magnesium aluminum silicate
A
structured vehicle system
4
Q
what is methylparaben
A
preservative
5
Q
what is polysorbate 80
A
wetting agent
6
Q
what is propylparaben
A
preservative
7
Q
what is sodium dihydrogen citrate
A
buffering agent or antioxidant
8
Q
what is sorbitol
A
sweetener
9
Q
what is water
A
vehicle
10
Q
what is xanthan
A
structured vehicle system
11
Q
what is carboxymethylcellulose sodium
A
structured vehicle system
12
Q
what is disodium EDTA
A
chelating agent
13
Q
what is potassium sorbate
A
buffering agent or preservative
14
Q
what is cetyl alcohol
A
emulsifier and thickening agent
15
Q
what is glycerin
A
humectant
16
Q
what is mineral oil
A
oil phase
17
Q
what is polysorbate 60
A
emulsifier
18
Q
what is propylene glycol
A
humectant
19
Q
what is sodium lauryl sulfate
A
emulsifier
20
Q
what is stearyl alcohol
A
emulsifier or thickening agent
21
Q
what is Butylated hydroxytoluene
A
Free radical stabilizer
22
Q
what is Ethylenediaminetetraacetic
acid (EDTA)
A
Chelates divalent metal
cations
23
Q
what is Sodium bisulfite
A
Antioxidant acting by
preferential oxidation
24
Q
what is • Methyl paraben
A
Preservative acting by
lipophilic adsorption
25
what is Benzalkonium chloride
Preservative acting by
| electrostatic adsorption
26
what is ascorbic acid
antioxidant and buffering agen
27
what is citric acid
Antioxidant
Buffering agent
Chelating agent
28
advantages of solutions
- They are homogeneous- don’t have to worry about stuff settling down
- Easy to manufacture bc it is pretty stable
- Good bioavailability bc it is already molecularly dispersed so easy to take up by the body
29
when does a buffer work best (has highest buffering capacity)
at pH closest to pKa value
30
how do you find pKa
-logKa
31
how do you find Ka
10^-pKa
32
what are the alcohol preservatives/where are they used
- ethanol: only in oral products
- benzyl alcohol: injectables
- chlorobutanol: injectables and opthalmics
33
when are acids active?
only in unionized (lipid soluble) form
34
what are the two acids we talked about? used where?
benzoic acid and sorbic acid - oral
35
what are the two paraben classes we talked about?
esters of p-hydroxybenzoic acid and quaternary ammonium compounds
36
characteristics of Esters of p-hydroxybenzoic acid
i. Used orally
ii. Hydrolyze rapidly at pH values above 7
iii. Lipophilic ones (propyl paraben and butyl paraben) best against mold and yeast
iv. Less lipophilic (methyl paraben & ethyl paraben) best used against bacteria
v. Not used on skin-causes irratation
37
characteristics of quaternary ammonium compounds
ii. Widely used in ophthalmics
iii. Very water soluble and fast acting
iv. Incompatibility issues due to positive charge
38
what three factors affect preservative action
i. only the free preservative is active
ii. only unionized species of weak acids are effective
iii. add more weak acid when pH>pKa to maintain effective concentration
39
examples of free radical scavengers
a. Propyl, octyl, dodecyl esters of gallic acid
b. BHA, BHT
c. Tocopherols, Vitamin E
40
examples of reducing agents
i. sodium bisulfite
| ii. ascorbic acid
41
examples of chelating agents
citric acid and EDTA
42
what is interfacial tension
liquid-liquid interface
43
what are surfactants
molecules that contain a hydrophilic and hydrophobic region and orient at the liquid-liquid or liquid-air interface and lower interfacial or surface tension
44
what are the types of surfactant
1. cationic
2. anionic
3. zwitterionic
4. non-ionic
45
what does having a high HLB mean? low HLB?
high: water like
low: oil like
46
why are emulsifying agent added?
to stabilize the emulsion
47
why do we use micelles
micelles have hydrophobic groups of the surfactant oriented toward the center of the micelle - capable of dissolving water insoluble drugs
48
what are the three reasons that emulsions are instable
1. creaming
2. coalescence
3. phase inversion
49
steps to manufacture an emulsion
*Dissolve all water-soluble ingredients in water
● Mix all oil-soluble ingredients in oil (heat if necessary to melt)
● Heat aqueous solution to same temp as oil solution
● Mix oil solution + water solution w mix
● Cool slowly
● Pass through colloid mill or homogenizer
50
the three characteristics of dispersion
a. Makes repulsive forces dominant
b. Particles repel each other and do not aggregate
c. Problem: particles settle as individual particles; leads to dense, compact sediment which
may be difficult to resuspend
51
the 4 characteristics of controlled flocculation
a. Repulsive and attractive forces are in balance
b. Particles are attracted to each other at the secondary minimum to form aggregates
(known as floccules)
c. Floccules settle to produce a sediment w a high volume
d. This type of sediment is easy to redisperse
52
what is newtonian flow
remains constant
53
what is non-newtonian flow
not constant
54
plastic non newtonian flow
threshold of shear stress to necessary to initiate flow
55
pseudoplastic non newtonian flow
no finite stress necessary to initiate flow
56
dilatant non newtonian flow
has high solids content
57
what is a polymer
● A large molecule made up of many small repeating units (parts)
58
examples of natural polymers
- Proteins (gelatin)
- Polysaccharides (cellulose, chitosan, alginic acid)
- Nucleic acids (DNA, RNA)
59
examples of synthetic polymers
- Polyethylene, poly(vinyl chloride); poly(tetrafluoro ethylene) aka Teflon; polyurethane;
polyacrylate; poly (p-phenylene terephthalamide/ Kevlar)
- Nylon; silicon rubber; rayon
60
what does polydispersity mean?
measure of the distribution of molecular mass in a given polymer sample
61
factors affecting Tg
● Polymer length: the longer, bulkier: the higher Tg
● Side chains: the bulkier, the higher Tg
● Crosslinking: the more crosslinked, the higher Tg
● Plasticizers
