Dermatology Flashcards
Epidermis
4-5 layers, primary barrier to drug absorption, drugs have to get to dermis to be absorbed, hypodermis (fat layer) has an affect on lipid soluble drugs
Primary Barrier
Stratum Corneum- rate limiting step, hydrophobic
Factors Affecting Drug Absorption
thickness, hydration, time, area of exposure, occlusion (more occlusion can help absorption like patch or plastic wrap) but have increased risk of bacterial growth, drug conc., size of molecule, age (hydration, thickness and sun sensitivity), temp and vasculature, cellular arrangement of skin
Location (very important for exam)
best absorption in mucous membranes, hardest place is the palms of hands and feet
Considerations of Vehicles
solubility, rate of release, increase hydration can increase absorption, stability of drug and chemical and physical interations
Formulations
ointments are the best at stopping evaporation, tincutres and wet dressings are the best when you want a drying effect
Topical Preps
lotions, gels, creams, ung, solutions, patches, advantages: longer steady state, prevent exposure to GI and bypass first pass metab.
Lotions
scented lotions are more drying, for drying effects,
Gels
non-greasy, cooling
Aerosols
drying effects, don’t have to rub in, more expensive
Powders
no need to rub in, can cake in wet areas (bad)
Creams
drying effects, greasy
UNG
good for hydration, not good for hairy areas
Common ADE
irritation, pruritis, erythema, redness, contact dermatitis, Urticaria
Topical ABX
prevent infection, deodorization, acne, single active ingredients or w/ corticosteroids or other ABX
Bacitracin
Gram (+), and anerobes, ADE contact dermatitis, poorly absorbed, found in Neosporin, used to decrease colonization
Polymixin B and Neomycin
Gram (-), many preparations, ADE contact dermatitis
Bacitracin Formulations
Alone, w/ Polymixin B and in triple ABX ugn w/ neomycin
Mupirocin
GRAM (+), impetigo, intranasal to decrease colonization
Altabax
Retapamulin, use for impetigo
Topicals for Acne
clindamycin, erythromycin, metronidazole, sodium sulfacetamide (absorbed, not to be used in pts w/ sulfa allergy) ADE: dryness, burning, irritation
Retinoic Acid
Tretinoin = Vit A, 10% to circulation, can cause mild erythema and peeling, may worsen over the first 4-6 weeks, lesions clear in 8-12 weeks, can thicken the epidermis and remove fine lines and wrinkles
Adapalene
Differin or in combo w/ benzoyl peroxide Epiduo, similar to tretinoin but less irritating
Tazarotene
Tazorac, (acne)
Azelaic Acid
Finacea- 6-8 weeks for full effect
Benzoyl Peroxide
antimicrobial to P acnes. ADE irritation, redness, Can bleach hair and clothing
Lotrisone
Betamethasone and Clotrimazole
Powder
best for athletes foot, but otherwise mostly ineffective
Topical Antivirals
for HSV 1 and 2, for cold sores, Abreva (docosanol), Zovirax 5%, Denavir 1% (penciclovir)
Topical Immunomodulators
Protopic (tacrolimus)
Elidel (pimecrolimus)
Aldara (imiquimod), ADE: pruritis, superficial erosion, Black box warning for malignancies
Ectoparasiticides
RID and NIX for head Lice, must use a nit comb, both OTC, RX: Ovide (malathion) and Lindane
Scabes (transferred from skin to skin contact)
Elimite or Acticin (permethrin) drug of choice, leave on for up to 14 hours, Crotamiton lotion and Lindane are Legend RX
Corticosteroids
Potency: Low-hydro, dexameth, betameth, TAC Med- hydrocor. val, desonide, High- fluocinonide, TAC Very High- clobetasol
Counseling
don’t occlude unless told otherwise, 1% systemic absorption, ADE: atrophy (wrinkled appearance), rosacea, drying, cracking, thinning, Cushing Syndrome
Toical NSAIDs
for OA, acute pain, actinic keratosis, PHN when used along dermatome (Voltaren) diclofenac
NDAID
less systemic absorption but still carry warning, don’t use w/ oral NSAIDs, increased risk of thrombotic events, GI bleeding, pts undergoing CABG procedure
