Lab Exam Flashcards
Where are lozenges placed?
Buccal cavity
Major ingredient in hard lozenges?
Sugar
Major ingredient in soft lozenges?
PEG
Major ingredient in gummy lozenges?
Gelatin (glycerinated gelatin)
Major disadvantage of lozenges?
Mistake for candy by children
Purpose of geometric dilution?
Ensure mixture is homogenous
Purpose of sieving?
Ensure uniform particle size
Why do we add powder slowly to the PEG?
We must ensure each addition is wetted before adding additional powder to prevent clumping. Too much, too fast will not result in uniform powder distribution
Why do we slightly overfill each cavity of the mold?
B/c PEG contracts upon cooling
Aux. label(s) for diphenhydramine lozenges?
“May Cause Drowsiness” & “Keep Out of Reach of Children”
3 Uses of semisolid dosage forms?
- Protectant 2. Emollient (keeps skin hydrated) 3. Vehicle for other medications
Would you use a glass ointment slab or an ointment pad when compounding an ointment?
Glass slab (it’s a hard, non-absorbable surface); ointment pads would absorb liquid and ointment
Why should metal spatulas be used to compound ointments?
Their flexibility and strength ensures there’s good shearing and mixing of the preparation
Purpose of small metal spatula?
- Removing preparation from the large metal spatula 2. transferring preparation into ointment jar
Another name for Polysorbate 80?
Tween 80
What are the steps involved in incorporating a liquid into an ointment base?
- Place semisolid base on ointment slab 2. Create depression (well) in centre of base 3. Pour liquid into well 4. Carefully spatulate small portions of the base into the liquid
Name 5 classes of ointment bases.
- Oleaginous/Hydrocarbon bases 2. Absorption bases 3. W/O emulsion bases 4. O/W emulsion bases 5. Water-soluble bases
Which class of ointment base will release drug more rapidly: oleaginous or water miscible? Why?
Water-miscible ointment bases will release drugs more rapidly. Water penetrates base > Drug gets dissolved > drug diffuses out of base
Coal tar: Greasiness? Spreadability? Occlusivity? Water/oil washable?
Non-greasy, easily spreadable, non-occlusive, water-
washable
Where does coal tar come from?
The destructive distillation of bituminous coal.
How is coal tar solution made?
a) 200 g coal tar + 500 g washed sand
b) 50 g Tween 80 + 700 ml of alcohol added to a)
c) Macerate mixture for 7 days in a closed vessel w/ frequent agitation
d) Filter macerated mixture and wash vessel w/ enough alcohol to give 1000 mL of final soln
LCD
liquor carbonis detergens (aka “coal tar”)
Why is Tween 80 added to coal tar?
Coal tar is hydrophobic, thus Tween 80 is used to incorporate it into various preparations.
What’s coal tar used for?
To treat local skin diseases (e.g. psoriasis)
Side effects of coal tar?
a) Itching
b) burning
c) redness
d) skin/hair/clothes staining
e) sensitivity to sunlight
What’s a paste?
semisolid dosage 20-50% of which is composed of finely dispersed solid in a fatty base
Difference b/w ointments and pastes?
Ointments have <20% solids, whereas pastes have between 20-50% solids
Why must powders be reduced in size as much as possible before being incorporated into a base?
Prevent grittiness in final product.
4 ways to reduce particle size?
Trituration, levigation, spatulation, pulverization by intervention
What is levigation?
Method of particle size reduction where a powder is mixed with a liquid (the levigating agent) in which it is insoluble
3 advantages of using levigating agents?
- Make preparations SMOOTHER
- make INCORPORATION easier
- decrease the amt of energy required to reduce particle size of powder
2 properties of GOOD levigating agents?
- Drug is INSOLUBLE in it
2. It is compatible with and similar to the ointment base being used
When do you add an aux levigating agent?
When there’re no ingredients in the preparation that could be used as a levigating agent.
Why don’t we add levigating agent when we have lots of powder to triturate?
Because the product will be runny.
When do we NOT use levigating agents? (4)
- when the solid is already very fine
- when we have a very small qty of solid that needs to be incorporated
- when the ointment base is soft
- when the final preparation is supposed to be stiff
What is the appropriate levigating agents for…
a) Oleaginous, absorption, & W/O emulsion bases?
b) Water-soluble and O/W emulsion bases?
c) Coal tar?
d) Peruvian balsam?
a) mineral oil
b) glycerol
c) Tween 80
d) Castor oil
T or F? We use less base when we use an aux levigating agent.
T
What is an appropriate amt of levigating agent?
Minimum amt needed to wet the powders so that a consistency of putty is achieved.
What type of emulsifying agent is acacia?
O/W
What type of emulsifying agent is stearic acid + triethanolamine?
O/W
What type of emulsifying agent is anhydrous lanolin?
W/O
What type of emulsifying agent is Span 80?
W/O
What’s a dye test?
a) Add water-soluble dye: if uniform colour, then O/W emulsion; if globular distribution, then W/O emulsion
b) Add oil-soluble dye: if uniform colour, then W/O emulsion; if globular distribution, then O/W emulsion
What’s a dilution test?
Add water
Stable, diluted emulsion? > O/W emulsion
Emulsion breaks apart? > W/O emulsion
What’s a drop test?
Take drop of unknown emulsion and place it into water
Drop spreads out? > O/W emulsion
Drop remains as a drop? > W/O emulsion
In suppositories, what is the purpose of acetaminophen?
analgesic
In suppositories, what is the purpose of hydrocortisone?
anti-inflammatory
In suppositories, what is the purpose of aminophylline?
bronchodilator
In suppositories, what is the purpose of diphenhydramine?
antihistamine, antiemetic
Aux label for rectal suppositories?
“Rectal Use Only”
Are PEG bases water soluble or fat soluble?
Water soluble
Is Witepsol bases water soluble or fat soluble?
Fat soluble
What lubricating agent is used for PEG suppository bases?
Mineral oil (Don’t want to dissolve the suppository base)
What lubricating agent is used for witepsol suppository bases (or any fat-sol suppository base for that matter)?
Glycerin (Don’t want to dissolve the suppository base)
About how long does it take for oleaginous bases to melt in the rectum?
3-7 mins
About how long does it take for PEG bases to melt in the rectum?
30-50 mins
4 disadvantages of PEG bases?
- Stinging sensation in sensitive tissues of vagina, urethra, and rectum
- Causes defecation reflex
- PEG is incompatible w/ large number of drugs
- PEG interacts w/ polystyrene containers
Which type of suppository would you expect to melt in a person’s hand? Ones made with fatty bases or water-sol bases?
Fatty bases > they have lower mp’s
Why don’t we pour suppositories into cold aluminum molds right away?
It’ll cause fractures and fissures to form in the suppositories.
Why do we pour suppositories SLOWLY?
Prevent air bubbles from getting trapped in the mold
Why do we pour suppositories CONTINUOUSLY?
Prevent layering
Why do we slightly overfill each cavity?
The PEG contracts upon cooling
What do we use to wrap each suppository?
1 inch squares of foil.
