Dermatologic Pharmacology Flashcards
rate limiting step drug absorption
stratum corneum
vehicle reservoir
to extend the release of dermatologic agent
routes of drug absorption
through stratum corneum
sweat ducts
sebaceous follicles
percutaneous absorption
concentration gradient estabilished
partition coefficient - drug ability to leave vehicle
diffusion coefficient
wet lesion
wet dressings
pulls moisture out as evaporates
ointments
most able to stop evaporation
dry skin
use cream or ointment
wet skin
use gel or lotion
transdermal patch
constant drug delivery
10yo M mountain bike wreck, abraded areas
tx approach - clean with soap and water
use of topical antibiotic debated - promote resistance
clean wound and remove debris**
MOA of neosporin
bacitracin - inhibit cell wall synthesis
polymyxin B - increases permeability of cell wall
neomycin - bind and inhibit 30S ribosomal subunit
bacitracin
gram positive
anaerobic cocci
polymyxin B and neomycin
gram negative coverage
5yo F, red sores around mouth, suspect impetigo
what antibiotic cover group A beta-hemolytic strep and staph aureus (including MRSA)
mupirocin
retapamulin
group A beta-hemolytic strep
strep pyogenes
tx of impetigo
non-bullous - topical therapy - mupirocin or retapamulin for 5 days
bullous - oral antimicrobial for 7 days
benefits of topical tx
fewer side effect
low risk of bacterial resistance
adverse of bacitracin and neomycin
contact dermatitis
acne
topical antibiotics
-less effective than benzylperoxide
clindamycin, erythromycin, metrondiazole, sodium sulfacetamide
MOA clindamycin
macrolide - inhibits 50S
MOA erythromycin
macrolide - inhibit 50S
MOA metrondiazole
damages DNA
MOA sodium sulfacetamide
sulfonamide - inhibit folic acid synthesis
organism in acne
proprionibacterium acnes
gram positive rod**
35yo M construction worker, itching of both feet, dermatophyte infection
-athletes foot tx?
azole
allylamine
butenafide
toinaftate
MOA azole
inhibit synthesis of ergosterol
-inhibits lanosterol 14-a-demethylase
for ring worm, athletes foot, etc.
also cutaneous candidiasis - vaginal yeast infection
MOA ciclopirox alamine
inhibit uptake of precursors of macromolecule synthesis
topical detmatomycosis, candidiasis, tinea versicolor
MOA allylamines
inhibit squalene epoxidase
terbinafine and naftifine
allylamines
MOA toinaftate
unknown
use of nystatin
cutaneous and mucous candida infection - thrush
swish and spit
amphotericin B
for systemic infection - broad antifungal coverage
fever, chills, hypotension, kidney dysfunction, liver, anemia
side effects of amphotericin B
also - long half life - lots of organ toxicity
esophageal candida
use azoles
MOA griseofulvin
inhibit fungal cell mitosis at metaphase
in dermatophyte infection
induces CYP enzymes
azoles
lots of drug rxns
terbinafine
high first pass metabolism
-accumulate in skin, nails, fat
tinea
dermatophyte function
capitis - scalp - oral
pedis - feet - topical
cruris - groin - topical
corporis - body - topical
candida infections
thrush - oropharyngeal - oral
esophageal - systemic
vulvovaginitis - topical - fluconazole
invasive - systemic antifungal
40yo M frequent cold sores
-organism is what?
herpes simplex type 1
tx for herpes simplex type 1
acyclovir, penciclovir, docosanil - modest benefit
docosanil is OTC
chronic suppression of HSV1
acyclovir valacyclovir
MOA cyclovirs
converted to pharmacologically active triphosphate metabolites - inhibit DNA synthesis and viral replication
MOA docosanol
inhibit fusion between plasma membrane and HSV envelope
-prevent viral entry and replication
immunomodulators
imiquimod - external genital warts
tacrolimus - atopic dermatitis - inhibit T lymphocyte activation - in transplant patients
oral for transplant rejection
tacrolimus
14yo F acne treatment
-benzoyl peroxide dries out skin
other options
topical retinoids
- tretinoin
- adapalene
- tazarotene
MOA - decrease cohesion epidermal cells - increased epidermal turnover
MOA benzoyl peroxide
releases free radical oxygen species - oxidize bacterial proteins - activity against P. acnes
no resistance occurs**
CI of retinoids
pregnant women
isotretinoin
oral retinoid
reduces sebaceous gland size
CI for isotretinoin
pregnancy**
need 2 forms of birth control
and monthly preg test
and cannot donate blood
iPLEDGE program
few lesions, little or no inflammation
mild acne
many lesions, significant inflammation
moderate acne
numerous lesions, extreme inflammation, significant scarring
severe acne
acne tx approach
1 - topical retinoid
2 - topical retinoid and antimicrobial
3 - topical retinoid, antibiotic, benzyl peroxide
4 - oral isotretinoin
<5% psoriasis on body
use topical
topical glucocorticoids
for psoriasis - don’t use for long term
coal tar
for psoriasis
-historical agent - older
calcipotriene
vit D3 analog
-up and coming mild to moderate psoriasis - <5% body - slow onset - no long term effects
tazarotene
topical retinoid
-for psoriasis
systemic psoriasis tx
if >5% body covered
methotrexate
acitretin
cyclosporine
not in pregnancy or alcohol
acitretin
not in kidney or liver dysfunction
methotrexate
not in kidney dysfunction or HTN
cyclosporine
methotrexate and phototherapy
systemic tx psoriasis
MOA methotrexate
inhibit dihydrofolate reductase - folic acid analog
with phototherapy for tx of psoriasis
TNF inhibitors
new psoriasis drugs
etanercept
infliximab
adalimuab
rule out TB**
cannot use with TB
TNF inhibitors
topical steroids
immunosuppressive and anti-inflammatory
grouped based on potency
low potency corticosteroids
hydrocortisone
high potency corticosteroid
betamethasone
clobetasol
keratolytic agent
salicylic acid
causes softening and dissolution of peeling of stratum corneum
pruritis and itching
antihistamines - can cause allergic dermatitis
also topical anesthetics
H1 antagonists
effective and treatment for itching
diphenhydramine and promethiaizine**
agents for hair growth
trichogenic agent
minoxidil - unknown MOA
finasteride
finasteride MOA
competitive selective inhibitor of 5-a reductase
-blocks T > DHT conversion
adverse - decreased libido, erectile dysfunction
pregnant women
should not handle finasteride
