Semisolids Flashcards
Topical applications are used for ___ and/or ____ absorption
Local + systemic
What is the target tissue of topical products?
INTO the skin
What is the target tissue of transdermal products?
THROUGH the skin (skin is generally not the target)
What is percutaneous absorption?
Drug absorption thru UNBROKEN skin both into the skin and into circulation
Ointment bases are chosen and used for their _____ effects and as ______
physical + vehicles
What are the 4 USP groups ointment bases are classified as?
- Oleaginous base
- Absorption base
- Water-removable base
- Water-soluble base
What kind of effect does oleaginous base have?
Emollient/moisturizing
(T/F) Oleaginous bases are water miscible
False
(T/F) Water + aqueous preparations may be incorporated in oleaginous bases, but w/ difficulty
True
What is generally used as a levigating agent for oleaginous bases?
Mineral oil
What is the MP of petrolatum?
38-60 degrees (C or F?)
(T/F) Petrolatum are generally used alone as a ointment base
False, used alone or in combination w/ other ingredients
Which is more esthetically pleasing?
A. Petrolatum
B. White Petrolatum
C. Yellow Ointment
B. White Petrolatum
Where is White Petrolatum found in?
Skin creams, lotions, lip balms
Which has a higher viscosity compared to petrolatum alone?
A. White Petrolatum
B. Yellow Ointment
B. Yellow Ointment
Absorption bases contain _____, which the amount depends upon the base
water
What are the two “types” of absorption bases?
- Permits incorporation of aqueous sol. and forms (W/O) emulsions
- Those that are (W/O) emulsions and permits incorporation of additional aqueous sol.
Which is more occlusive, oleaginous or absorption base?
Oleaginous bases
Absorption bases are (easily/not easily) removed from skin w/ water due to oily external phase
not easily
Lanolin is purified wax-like substance obtained from ____ wool
sheep
Lanolin contains less than ___% water
0.25
Lanolin permits formulation of more (hydrophilic/lipophilic) drugs
hydrophilic
Water removable bases are also known as ____ emulsions
(O/W)
Water removable bases are commonly called ______
creams
Water removable bases are vehicles for solid, liquid or _______ drugs
non-hydrolyzable
Water removable bases have an external phase which is ______
aqueous
Water soluble bases (do/do not) contain oleaginous components
do not
Water soluble bases are mostly used for incorporation of _____ substances
solid
PEG viscosity ____ w/ MW
increases
What kind of bases would be the choice for rapid release of lipophilic drugs?
Water-soluble and water-removable bases
What are the two methods of preparation of ointments?
- Incorporation (mortar/pestle electronic or not)
2. Fusion (melted and cooled)
Ointments (solids)
If particle size needs to be reduced, this is done by ________
levigation
Ointments (solids)
Materials are added to the base by ______ dilution
geometric
What are added last according to the fusion method?
Heat sensitive or volatile materials
What is typically not mixed well by incorporation and are prepared by fusion?
Beeswax, paraffin, strearyl OH, high molecular weight PEGs
Topical applications are not required to be sterile except for _____
ophthalmic preparations
Labeling of ointments (as per USP) includes….?
- Type of base used
- Storage conditions
- Administration
What kind of agent is added to make gels?
Gelling agent
What kind of gelling agents are there?
- Synthetic polymers
- Cellulose derivatives
- Natural gums
In a single phase gel, macromolecules are _____ distributed throughout the liquid
uniformly
In a two-phase gel, gel mass consisting of floccules are referred as _____
magma
(T/F) Gels can be frozen
False
(T/F) Gels are stored in tight containers to prevent water loss
True
Gels are formed in three methods which are…?
- Dispersing molecule in continuous phase
- Change pH
- Reducing continuous phase
Pastes contain a larger proportion of ____ than ointments
solids
A portion of the base of a ______ may be used as a levigating agent
paste
Plasters are applied to the skin for ______ contact
prolonged
Glycerogelatins form a _____ ______ that may be protected by a dressing
pressure bandage
Which semisolid can be used to treat varicose ulcers
Glycerogelatins (specifically Zinc gelatin)
____-dose tubes may be prepared w/ a tear-a-way tip and normally do not require antimicrobial preservatives
single
Stratum corneum is a _______ tissue
keratinized
Stratum corneum is about ____mm thick
15
Stratum corneum is composed of partially ____ cells
desiccated/dead
Stratum corneum acts as a _______ membrane with drugs penetrating by passive diffusion
semipermeable
What kind of drugs are good candidates for passive diffusion thru stratum corneum?
Drugs w/ both aqueous + lipid solubility
When does a drug become available for systemic abosrption?
When it reaches vascularized dermis
To allow drugs to penetrate the upper dermal layers, you can add ______ enhancers to topical vehicle
penetration
(T/F) Oleaginous bases provide less occlusion and emollient effect than hydrophillic/water-washable bases
False; provide more occlusion
(T/F) Paste offer about the same occlusion and effectiveness versus ointments at absorbing serous discharge
False; offer more occlusion
Major route of drug absorption is via the ______
cornea
Cornea is a ____ layer structure
3 (lipophilic epithelum, hydrophilic stomal layer, and a less lipophilic endothelum)
(Lipophilic/Hydrophilic) drugs are more capable of crossing the layers of the cornea
Lipophilic
When sterilizing ophthalmic RXs, steam sterilization or ethylene oxide are ineffective due to….?
inability to penetrate ointment base
What’s wrong with using heat sterilization on ophthalmic bases?
Penetrates base, but may cause stability issues
