part 4 Flashcards
what is a tablet direct compression excipient? give an example
ditab (dibasic calcium phosphate)
used in DIRECT COMPRESSION tablet formulations. saves money
why is a tablet disintegrant used?
used in SOLID DOSAGE FORMS to promote the disruption of the solid mass into smaller particles which are MORE READILY DISSOLVED/dispersed
give 2 popular tablet disintegrants
starch and avicel (microcrystalline cellulose)
explain how starch works as a tablet disintegrant
it swells when in contact with water which causes the powder to break down and ensure dissolution
is avicel natural or synthetic? what is it used as?
synthetic tablet disintegrant
what are tablet/capsule glidants? give 3 examples
used in tablet and capsule formulations to improve the FLOW PROPERTIES of the powder mixture
colloidal silica
cornstarch
talc
what is a tablet lubricant used for?
give 5 examples
used in tablet formulations to reduce FRICTION DURING TABLET COMPRESSION
calcium stearate
magnesium stearate
mineral oil
stearic acid
zinc stearate
without a tablet lubricant, what would happen?
the surface of the tablet would not be smooth
what are tablet/capsule opaquants used for? give an example
used to render a capsule or tablet coating opaque
titanium dioxide (ingredient in susnscreen_
tablet/capsule opaquant may be used alone or in combination with ______
colorant
how does being opaque help the tablet?
it blocks the light which aids in stability
what is the function of a tablet polishing agent?
give 2 examples
used to impart an attractive sheen to coated tablets
carnauba wax and white wax
what is the function of a tonicity agent?
to render a solution similar in OSMOTIC CHARACTERISTICS to physiological fluids.
name 3 types of preparations in which tonicity is a consideration
ophthalmic
parenteral
irrigation fluids
give 2 examples of tonicity agents
sodium chloride
dextrose
explain the difference between sodium chloride and dextrose as tonicity agents
osmotic pressure is related to the NUMBER OF PARTICLES.
sodium chloride produces 2 particles upon dissociation while dextrose only produces 1. therefore, 1 mol dextrose = 0.5mol NaCl.
NaCl is thus preferred because less of it is needed to accomplish the same function, but sometimes dextrose is needed in some patients for nutritional value
a hypotonic solution will cause a cell to….
burst (lyse)
what is the depressing freezing temp
0.52
define a vehicle
a carrying agent for a drug substance
true or false
vehicles are only used for oral preparations
false – oil and parenteral
generally, oral liquids are aqueous preparations (___________) or hydroalcoholic (__________)
syrups
elixirs
parenteral solutions for intravenous use are ______ whereas intramuscular injections are ______
IV = aqueous
IM may be aqueous OR oleaginous
how many different kinds of vehicles are there?
name them
3:
-flavored/sweetened
-oleaginous
-sterile
give 6 examples of flavored/sweetened vehicles
acacia syrup
aromatic syrup
aromatic elixir
cherry syrup
cocoa syrup
syrup
give 4 examples of oleaginous vehicles
corn oil
mineral oil
peanut oil
sesame oil
give 2 examples of sterile vehicles
bacteriostatic water for injection
bacteriostatic sodium chloride for injection
which is preferred – sterile water for injection or bacteriostatic water for injection?
sterile water for injection because it does not contain preservatives
a viscosity increasing agent is used to…..
change the consistency of a preparation to render it MORE RESITANT TO FLOW
name 3 dosage forms in which viscosity increasing agents are used
suspensions to slow sedimentation
ophthalmic solutions to enhance contact time (methylcellulose)
to thicken topical creams
name 4 factors to consider under “appearance and pallatability”
flavoring pharmaceuticals
sweetening pharmaceuticals
coloring pharmaceuticals
preservatives
true or false
preservatives kill microorganisms
FALSE – they inhibit their growth
true or false
sterilization kills microorganisms
true
What is the ideal solubility of the preservative selected?
it should be soluble enough in water to have adequate concentrations in the aqueous phase.
An emulsion is oil and water. The preservative has to dissolve in both phases
when selecting a preservative, the preservative must prevent….
the growth of the type of microorganisms considered the MOST LIKELY CONTAMINANTS of the preparation
what can you say about the ideal dissociation of the preservative selected
the proportion of the preservative remaining undisociated at the pH of the preparation makes it capable of
-penetrating the microorganism
-destroy its integrity
what are the main 3 requirements for the concentration of the preservative selected?
it must be nonirritating, nonsensitizing, and nontoxic to the patient
what are the % preservative limits for:
- Oral
- Parenteral
~1% for oral
~0.1% for parenteral
the preservative selected must have adequate stability.
explain thus further
it cannot be reduced in concentration by chemical decomposition or volatilization during the preparation’s shelf life
true or false
the preservative must be completely compatible with all other formulative ingredients and does not interfere with them, NOR do they interfere with the preservative’s effectiveness
true
true or false
it is not a requirement that the preservative selected does not adversely affect the preparation’s container/closure
false– it is a requirement
for oral preparations, do we prefer to use alcohol or preservatives?
alcohol
define:
- Suspensions
- Emulsions
- Foams
suspensions: dispersion of solid in liquid
emulsions: dispersion of liquid in liquid
foams: dispersion of gas in liquid
name some heterogeneous dosage forms
what does this mean?
suspensions. emulsions, and foams
they have 2 phases
what does “interface” mean
when phases exist together, the “interface” is the boundary between the 2 phases
what is the term for the fact that the interface are different from those in the bulk of each phase?
interfacial phase (it’s its own phase)
an emulsion is what kind of interface?
liquid-liquid interface
YLL
a suspension is what kind of interface?
liquid-solid interface
YLS
can solid-solid have interfacial tension?
YES
ex: powder API forming an interface with the powder excipients
Yss
can gas-gas form an interface?
NO
explain gas-liquid interface
gas-liquid
YLV
a liquid surface where the body of water is exposed to the atmosphere (ex: a lake)
is gas-solid interface possible?
yes
Ysv
like gas hovering over a table top
autoclaving is an example of….
sterilization
name 6 methods of preservatives to inhibit the growth of microorganisms
(REMEMBER: NOT KILLING, INHIBITING GROWTH)
-partial lysis (modification of cell membrane permeability and leakage of cell components)
-lysis and cytoplasmic leakage
-irreversible clotting (coagulation) of cytoplasmic constituents (protein precipitation)
-inhibition of cell metabolism by interfering with enzyme systems/inhibition of cell wall synthesis
-oxidation of cell constituents
-hydrolysis
1 of the modes of action for preservatives is the irreversible coagulation of cellular constituents.
give an example of this
protein precipitation
name 2 ways in which preservatives can inhibit cellular metabolism
-interfering with enzyme systems
-inhibition of cell wall synthesis
true or false
only the unionized form of a preservative possesses preservative capability
true
bc the ionized form cannot penetrate the cell membrane
alkaline preservatives are more effective at which pH conditions?
alkaline conditions because they will be unionized
define adhesive force and cohesive force
adhesive force = attracting force between 2 DIFFERENT molecules
cohesive force = attracting force between the SAME adjacent molecules
differentiate between interfacial tension and surface tension.
what do they have in common?
interfacial tension = force per unit length existing at the interface betwen TWO IMMISCIBLE LIQUID PHASES (no gas involved)
surface tension = force per unit length existing at the interface between LIQUID-VAPOR or SOLID-VAPOR phases
BOTH are temperature dependent. if the temperature changes, the value changes
surface tension is mainly used to refer to….
gas—-liquid and gas—–solid
an emulsion is an example of interfacial tension or surface tension?
interfacial tension
liquid—-liquid
explain how surface/interfacial tension is temperature dependent, using water as an example
at 0 degrees celsius, the surface tension is 76.5 dynes/cm
-this means it requires higher energy for the water to evaporate
-at 20 degrees celsius it gets a little easier to evaporate with a surface tension of 72.8 dynes/cm
-HOWEVER, at very high temperatures (75 degrees C), the tension lowers to 63.5 dynes/cm, meaning it’s very easy for the water to evaporate
in the case of water, as temperature increases, surface/interfacial tension___________
decreases
true or false
surface tension is a constant and only a change in temperature can change the value
TRUE
Which substance has a VERY HIGH interfacial tension against water? what does this mean?
mercury — 375 dynes/cm against water
this means that mercury doesn’t normally have interaction with water. it needs very high energy input to interact with water
which will have HIGHER surface area in water – oleic acid or mercury?
why?
oleic acid will have a higher surface area than mercury in water
this is bc mercury has a very high interfacial tension with water (375) and oleic acid is small (15.6)
mercury will form a small droplet while oleic acid will most likely spread
for emulsions, what range of interfacial tension is desirable?
~10-20dynes/cm
what is the surface tension of water?
does chlorofoam have a higher or lower surface tension as compared to water? what does this mean?
surface tension of water = 72.8dynes/cm
chlorofoam has a LOWER surface tension at 27.1dynes/cm
this means it is easier for chlorofoam to evaporate than water. easier to go from 1 phase to another
does olive oil have a high or low interfacial tension?
pretty low — 22.9dynes/cm
what is the surface tension symbol
(Y) gamma
give the formula for surface tension
Y= fb/2L
Y=surface tension
fb= force required to break the film
L=length of movable bar
in the formula for surface tension, why is the L multiplied by 2?
because the film is double sided
fb=….
m * g
where g= 981cm/sec squared
what is the value of g constant
981 cm/sec squared
what is the formula for force
f=Y * 2L
Y=surface tension
give the formula for work
dW= f* ds
f= Y * 2L
ds=change in surface area
surface free energy is a measure of…..
surface free energy change per unit area increase
what is the formula for surface area increase
dA= 2L * ds
give the formula for surface free energy
dW = Y * dA
Y = fb * 2L
dA = ds *2L
if the surface tension is low, it requires ____ energy to extend the surface area
LESS energy
when energy escapes, the surface area is ______
reduced
name the 2 main methods for the measurement of surface and interfacial tension.
which is preferred to measure surface tension and why?
Capillary rise method and the DeNouy ring method
capillary rise method is preferred to measure surface tension because it is much cheaper than the alternative
HOWEVER, the capillary method can’t measure interfacial tension and the DeNouy ring method can. it is MORE PRECISE
explain how the capillary rise method works
if the adhesive force (between the liquid molecules and the capillary wall) is greater than the cohesive force, the liquid wets and spreads over capillary wall. (rises).
the surface tension can then be measured (NOT INTERFACIAL)
y = 1/2 (rhp) *g
r=radius of capillary tube
h=height that the sample rises
p=density
g=constant (981cm/sec squared)
in the capillary rise method for measuring surface tension, ___ will become constant. why?
h will become constant because equivalence between adhesive and cohesive force will be reached
The deNouy ring method measures the force needed to….
detach a platinum-iridium ring
what is the formula for surface tension in the DeNouy Ring method
Y= dial reading in dynes/2 * ring circumference
all * correction factor (given by the manufacturer)
true or false
in very small particles, high energy exists
true
if cohesive force is ____ than adhesive force, spreading will occur and a film will be formed
this exists in the case of…..
LESS
oleic acid and water
when oleic acid is placed on water, how many forces exist?
name them
3 forces–
oleic acid - oleic acid (cohesive)
water - water (cohesive)
oleic acid - water (adhesive)
will mercury spread on the surface of water?
no
true or false
the cohesive force of mercury is very high
true – will not spread
true or false
the cohesive force of oleic acid is higher than the adhesive force
FALSE
which has lower surface tension – mercury or oleic acid?
oleic acid
low concentration of surfactant will go where?
to the surface
once the surface is occupied (CMC), it will go to the bulk
When will surfactants have NO EFFECT on reducing surface tension?
at concentrations above CMC (when they start to go to the bulk)
what is duplex film?
thickness higher than 100 angstroms
true or false
duplex film is independent between the surface (oleic acid/air) and the interface (oleic acid/water)
TRUE
YL=…
surface tension of spreading liquid (top liquid)
YS=….
surface tension of sublayer liquid
YLS=…
interfacial tension between 2 liquids
Wa=….
work of adhesion
YL+YS-YLS
Wc=….
work of cohesion
2YL
give the formula for spreading coefficient
S = YS-(YL+YLS)
many _____ substances fail to spread on water (polar or nonpolar)
nonpolar
what does a high S value mean?
how is S measured
S= initial spreading coefficient. measured in dynes/cm
high S = high spreading
true or false
ethyl alcohol has a low S value
FALSE – high S value due to polar functional groups
liquid petrolatum has a ____ S value (low or high)
LOW – very nonpolar
