Dermatologicals Flashcards
what are the 5 layers of the epidermis
stratum corneum stratum lucidum stratum granulosum stratum spinosum stratum germinativum
what are the layers of the skin
epidermis
dermis
subcutaneous tissue
what is the pH of the epidermis
acidic (pH=5.5)
role of the stratum corneum
major permeability barrier of the skin, controls percutaneous absorption
role of the stratum lucidum
responsible for skin stretch
role of the stratum granulosum
Site of biochemical activity (bioreactor)
role of the stratum spinosum
Change their morphology based on pressure placed on the skin
role of the stratum germinativum
□ Nucleated basal cells: dividing (mitosis) layer which replaces the shedding cells of stratum corneum
where are the nerves and blood vessels of the skin located?
dermis
what is the sink effect
Vascular supply: sink effect (dugs don’t accumulate in the skin–>the concentration gradient is always optimal
what is the function of the subcutaneous tissue
thermal barrier (Passive barrier doesn’t actually regulate heat: dermis blood vessels contract or expands based on heat) mechanical cushion
functions of the skin
elasticity
protective
what is an oleaginous base
○ Single phase–>ointments
Properties: Hydrophobic Greasy Non-water washable occlusive emollient
what does occlusion mean
formation of an impermeable layer on the skin to prevent evaporation of water
what does emollient mean
softens skin
advantages of oleaginous bases
Very stable vehicles
Non-irritating
Non-sensitizing
High compatibility with drugs (generally neutral)
disadvantages of oleaginous bases
Greasiness
Stains clothing
Difficult to remove
Low patient acceptance (
what are the liquids used to form oleaginous bases
fats and fixed oils Examples: almond, corn, cottonseed, olive, peanut, safflower, sesame seed, soybean oils
what are semisolids used to form oleaginous bases
Petrolatum and white petrolatum
what solids are used to form oleaginous bases
waxes
paraffin
do oleaginous bases need penetration enhancers
Yes
how do permeation enhancers work
fluidization of the stratum corneum lipids
do oleaginous bases require antimicrobials
No as they dont contain water
do oleaginous bases need levigating agents
yes when incorporating a powder into the ointment
they are less than 5% of the formula
mineral oil
or the base can be used
describe the process of fusion
melt the components together starting with the lowest melting point
then its is cooled with constant stirring until congealed
what are absorption bases
Non-water washable bases Hydrophobic Greasy Anhydrous; hydrophilic components provide water-absorbing properties Upon water addition form w/o emulsions Occlusive Emollient Used in oozing conditions
main components of absorption bases
Fats and fixed oils
Mineral oil
Petrolatum and white petrolatum
Waxes
other excipients of absorptive bases
All have water-absorbing capacity
Upon addition of water, form w/o emulsions
ex: lanolin, hydrous lanolin, cetyl alcohol, stearyl alcohol, stearic acid, oleic acid, glycerol monostearate, cholesterol