Topical agents Flashcards
what are the living layers of the epidermis?
basal
spinous
granular
in which epidermal layer does most of the cell division occur?
basal
which epidermal layer synthesizes the most epidermal proteins?
spinous
which epidermal layer is the major barrier to percutaneous absorption? why?
corneum
lipid-enriched extracellular matrix with lipid bilayers produced by corneocytes
definition: corneocytes
flattened and lipid-depleted keratinocytes composed of keratin granules
what are the absorption pathways of intact skin?
- appendages (shunt)
- transcellular (corneocytes)
- intracellular lipid domains
what is the most common absorption route for small uncharged molecules?
intracellular lipid domains
which vehicles are convenient for scalp and hairy areas?
lotions gels solution foams aerosols
which vehicles are convenient for intertrigous areas (rubbing) without causing maceration?
creams
lotions
solutions
lotions gels solution foams aerosols
are useful for what areas?
scalp and hairy
creams
lotions
solutions
are useful for what areas?
intertrigous areas (rubbing) without causing maceration
what vehicle is best for dry and scaly skin?
ointment
what vehicle is best for wet and oozing skin?
tinctures
ointment is best for what type of skin?
dry and scaly
tinctures are best for what type of skin?
wet and oozing
what is the rate limiting step for percutaneous absorption?
passage through corneum
definition: partition coefficient
partitioning of drug from vehicle into stratum corneum
definition: drug diffusion coefficient
molecular aspects of the drug allowing diffusion across skin layers
what does Fick’s law describe?
rate of absorption or flux of substance across barrier
what are the drug factors affecting PCA?
concentration
lipophilicity
molecular size
how does hydration of skin affect PCA?
increase
is there first pass metabolism of topical drugs?
no
what are the general drug classes used to treat acne?
antibiotics retinoids salicylic acid oral contraceptives anti-androgens
what is the primary bacterium responsible for acne?
proprionibacterium acnes
what is the main way to reduce the effects of acne?
reduce sebum production
what are the topical agents used to treat acne?
erythromycin clindamycin metronidazole sodium sulfacetamide azelaic acid benzoyl peroxide salicylic acid
what is the MOA of benzoyl peroxidase?
comedolytic (destroys plugs)
keratolytic (dries and desquamates)
what are the MOAs of salicylic acid?
increases solubilization of stratum corneum by altering keratin by breaking hydrogen bonds
clears comedones by desquamation
retinoid agents are used for what purposes?
acne
psoriasis
skin aging
skin cancer
what are the adverse effects of the retinoids?
photosensitivity
tretinoin is what class of drug?
retinoid
what are the therapeutic uses for tretinoin?
acne
photoaging
what is the MOA of tretinoin?
- decrease cohesiveness of follicular epithelial cells responsible for producing microcomedones
- comedolytic
- reduces keratinization
tretinoin whould NOT be applied in combination with what other drug? why?
benzoyl peroxide
BP inactivates it
what is the main adverse effect of tretinoin?
pregnancy (category C - possible to use but caution)
photosensitivity
adapalene is what class of drug?
retinoid
which retinoid can be combined with benzoyl peroxide?
adapalene
what is the MOA of isotretinoin?
suppress sebum production by inducing apoptosis in sebum producing cells of sebaceous glands
what is the primary adverse effect of isotretinoin?
teratogenesis
what class of drug is tazarotene?
retinoid
what class of drug is isotretinoin?
retinoid
which drugs inhibit sebaceous gland function?
antiandrogens
oral contraceptives
isoretinoin
what class of drug is acitrecin? what is the therapeutic use?
retinoid
psoriasis (severe, recalcitrant)
what increases the elimination time of acitrecin?
alcohol
what class of drug is calcipotriene? what is the therapeutic use?
vitamin D receptor antagonist
psoriasis - moderate to severe
what are the strength ratings of hydrocortisone, mometasone furoate, and clobetasol proprionate?
hydrocortisone - low
mometasone furoate - intermediate
clobetasol proprionate- high
what constitutes photochemical therapy? what are the therapeutic uses?
psoralen plus UVA light
alopecia
cutaneous T cell lymphoma
eczema
psoriasis
what are the psoralen agents?
methoxsalen
trioxsalen
