Dermatologics Flashcards
Layers of the Epidermis (from Superficial to Deep)?
“Carter Licks Gooch & Sweaty Balls”
1) Stratum Corneum
2) Stratum Lucidum
3) Stratum Granulosum
4) Stratum Spinosum
5) Stratum Basale
pH of Epidermis?
5.5
The Epidermis is comprised of what cell types?
1) Keratinocytes (synthesize Keratin)
2) Melanocytes (synthesize Melanin pigment)
3) Dendritic / Langerhans Cells (immune cells that determine adaptive immune response post-pathogenic exposure)
Stratum Corneum other name?
Carter 24/7 :)
Horny Layer
Stratum Lucidum other name?
Clear Layer
Stratum Granulosum other name?
Granular Layer
Stratum Spinosum other name?
Prickle Cell Layer
Stratum Germinativum / Basale other name?
Basal Layer
Major role of Stratum Corneum?
-Permeability Barrier
-Ctrl of Percutaneous Absorption
The Stratum Corneum also undergoes a phenomenon known as “Desquamation”. Describe this process.
-Cells from top outermost layer of skin are removed.
-This process enables skin to continuously create uniform “brick & mortar” structures. Also creates a barrier that enables the skin to rehydrate & resist assault from pathogens.
T or F: Cells of the Stratum Lucidum layer are nucleated.
False… Are anucleated.
What role does the Stratum Lucidum play?
-Skin stretchability.
-Contains protein that degenerates skin cells.
-Lowers skin friction (espec. in soles of feet & hands).
Topical prodrug activation takes place first at what Epidermal layer?
Stratum Granulosum
Role of Stratum Granulosum?
-Bioreactor Site (duh Prodrug last card stupidddd).
Role of Stratum Spinosum?
-Filament Bundles are subject to constant pressure & friction; thus, this layer helps the skin resist abrasion.
T or F: Cells of Stratum Germinativum are nucleated.
True!
T or F: The Stratum Germinativum layer consists of multi-layered cuboidal / columnar cells.
False… Is a singular layer.
What is the normal turnover time of cells contained within the Basal (ie. S. Germinativum) Layer?
28d = Normal… 4d in Psoriatic patients.
Given that cells of the Basal Layer are nucleated, what important role do they play as it pertains to the overall functioning of the Epidermis?
-Because they are capable of dividing via Mitosis, provide Germinal Cells necessary in order to regenerate Epidermal sublayers.
The Dermis is comprised of ___% Collagen & ___% Elastin.
75%; 4%
What cell types are contained within the Dermis?
Fibroblasts, Mast Cells, Histiocytes
T or F: The Dermis is supplemented with rich Neurological & Vascular supplies.
True.
What are the three primary roles of the Dermis?
-Structural Support
-Thermoregulation
-Sensation
Average pH of the Dermis?
7.2
Role of the Hypodermis & Subcutis (ie. Subcutaneous Tissue)?
-Energy Storage
-Connect Dermis to Muscles & Bones
-Insulation / Cushioning
Why does our skin tend to sag as we age?
Shrinking Hypodermis
The Stratum Corneum requires ___-___% water to maintain its bendability (otherwise it chaps, cracks & splits).
10-20%
Sebaceous & Eccrine Sweat Glands contribute secretions to the Acid Mantle, which provides the skin with protective abilities. What is the pH of this Acid Mantle?
4.2 - 5.6
How many times less permeable is the Stratum Corneum (vs. other bodily membranes)?
10 000x less
Is the amount of drug penetrance through the “Shunt Route” (ie. Hair Follicles & Glands) important to take note of?
-Negligible… Follicles & Glands contribute 0.1% of total skin surface area.
UVB radiation induces burning of the skin. At what wavelength range does this occur?
290 - 320nm
UVA radiation is less damaging to the skin, but still contributes to aging & pigmentation processes. At what wavelength range does this occur?
320 - 400nm
How does the skin respond to UV radiation?
-Erythema
-Pigmentation
-Epidermal Thickening
-Chronic Rxn’s
-Aging
-Pre Maligancies
-Malignancies
What is the major rate-limiting barrier to transdermal drug delivery?
Stratum Corneum
Provide an example of a condition that impacts the barrier function of the Epidermis.
Atopic Dermatitis
What important Physicochemical properties must Dermatological formulations possess?
-Active Ingredient / Adjuvant Stability
-Uniform particle size & distribution within the Dispersed Phase
-Prevention of water loss / volatile compound formation
-Homogeneity
What factors affect vehicle selection in terms of optimizing bioavailability?
-Skin Disease / Condition
-Drug Release Rate from Vehicle
-Percutaneous Absorption Promotion
-Occlusion Requirement
-Drug Stability in Ointment Base
-Drug influence on base consistency
Ointments are comprised of </= ___% H2O & Volatiles, and >/= ___% Hydrocarbons, Waxes, or PEGs as the vehicle for external skin application.
</= 20% Water
> /= 50% HCs, Waxes, PEGs
Creams are comprised of >___% H2O & Volatiles, and <___% Hydrocarbons, Waxes, or PEGs as the vehicle for external skin application.
> 20% Water
< 50% HCs, Waxes, PEGs
Pastes are semisolid dosage forms that contain large proportions (ie. ____ - ____%) of solids, finely dispersed in a fatty vehicle for external skin application.
20 - 50% solids
What is the role of a Gelling Agent?
Provide Solution Stiffness &/or Colloidal Dispersion
What are the classes of Derm Vehicles?
Hydrocarbon Bases
Absorption Bases
Emulsifying Bases
Water Soluble Bases
Ointments differ from Creams how (regarding water / oil composition)?
Ointment: Mostly anhydrous (may contain dissolved or dispersed API).
Cream: Contains both oil & water.
Non Water Washable Bases include what?
Oleaginous / HC Bases
Absorption Bases
W/O Emulsion Bases
Water Washable Vehicles include what?
O/W Emulsion Bases
Gel Bases
Hydrophilic Bases
Emulsifying Bases
What are some examples of Hydrocarbon / Oleaginous Bases?
Petrolatum
Wax
Synthetic Esters
What are some examples of Absorption Bases?
Anhydrous: Hydrophilic Petrolatum, Anhydrous Lanolin
W/O Emulsion: Lanolin, Cold Cream
Examples of Emulsion Bases?
Hydrophilic Ointment
Vanishing Cream
Examples of Water Soluble Bases?
PEG 400 + 4000 (40 : 60 ratio)
Propylene Glycol + Ethanol + 2% w/w HPC
The addition of a W/O Emulsifier transforms an Oleaginous Base into what (Slide 44 Diagram)?
Absorption Base
The addition of an O/W Emulsifier transforms an Oleaginous Base into what (Slide 44 Diagram)?
Emulsifying Base
Major property of Hydrocarbon / Oleaginous Bases?
HIGHLY OCCLUSIVE (increase skin hydration by preventing water evaporation)
Issues with Hydrocarbon / Oleaginous Bases?
-Greasy (contributes to low patient compliance)
-Staining
-Hard to remove from skin
Main ingredients of Oleaginous Bases are what?
1) Fats / Fixed Oils & Mineral Oil
2) Petrolatum / White Petrolatum
3) Waxes
4) Paraffin
What is the big issue with Fats / Fixed Oils being used in Oleaginous Bases?
Rancidity (upon air / light / high temp exposure)
Primary roles of Petrolatum / White Petrolatum in Oleaginous Bases?
-Act as an Emollient (ie. Skin Softener).
-Occlusive (moisturizes skin by preventing water evaporation).