Dermatologic Pharmacology Flashcards
What are the variables of percutaneous absorption? (4)
Regional: some places are more absorbent than others (axilla > forearm, etc.).
Concentration gradient
Dosing schedule: long half-life of skin reservoir may allow for once daily dosing.
Vehicles/occlusion
What is a cream made of?
What are some characteristics of application of creams?
They are a better treatment option than ointments for what kind of skin conditions?
Half water/half oil with an emulsifier.
They spread easily, are well-absorbed and wash off with water.
They are better for oozing/”wet” skin conditions.
What is an ointment made of?
What are some characteristics of application of ointments?
They are a better treatment option than creams for what kind of skin conditions?
20% water and 80% oil.
They feel greasy and are “occlusive”.
They are better for dry skin since they trap moisture.
What provides for more complete absorption of the active ingredient: creams or ointments?
Ointments
What is most likely to lead to an allergic reaction: creams or ointments?
Ointments
What is the use of the following moisturizer components?
Emollient
Humectants
Horny substance (keratin) softeners
Emollient: form an oily layer on top of the skin that traps water in the skin.
Humectants: draws water into the outer layer of the skin.
Horny substance (keratin) softeners: loosens the bonds between the top layer of cells, which helps dead skin fall off and retain water; it makes the skin smoother.
What is the use of the following in sunscreen?
PABA
Benzophenones
Dibenzoylmethanes
PABA: active in the UVB range (redness, aging, carcinogenesis).
Benzophenones: active in a wider range than PABA, but is less effective.
Dibenzoylmethanes: active in the UVA range (aging and cancer); useful in drug-induced photosensitivity.
What is the utility of chlorhexidine?
What is its MOA?
It is a broad-spectrum antimicrobial agent widely used in homes/hospitals due to general efficacy on skin (and oral mucosa) and low irritability.
Low concentrations affect membrane integrity; high concentrations cause congealing of cytoplasm.
Under what condition is soap and water a better handwashing option than alcohol-based hand disinfection?
C. difficile
What is the indication of Becaplermin?
What is its MOA?
What is the black-box warning associated with it?
Treatment of chronic diabetic foot ulcers.
It is a PDGF that promotes cell proliferation and angiogenesis.
The use of >3 tubes increases the risk of malignant complications (4x).
Bacitracin
MOA
Coverage
Side-effects
MOA: inhibition of bacteria cell wall synthesis.
Coverage: G+ bacteria, anaerobic cocci, Neisseria, Tetanus and Diphtheria.
Side-effects: allergic dermatitis - poorly absorbed through skin, so systemic toxicity is rare.
Neomycin
MOA
Coverage
Side-effects
MOA: binds to 30S subunit and inhibits protein synthesis.
Coverage: G- bacteria.
Side-effects: allergic dermatitis - poorly absorbed through skin, so systemic involvement is rare.
Polymyxin B
MOA
Coverage
Side-effects
MOA: binds to phosphor-lipids to alter permeability and damage the bacterial cytoplasmic membrane.
Coverage: G- bacteria like Pseudomonas, E. coli, Enterobacter and Klebsiella.
Side-effects: rarely a allergic reaction.
What is the MOA of the antifungal “-azoles”?
What is the indication of the following? Miconazole Clotrimazole Efinaconazole Ketoconozole
Blocks ergosterol synthesis.
Miconazole: vulvovaginal candidaisis.
Clotrimazole: vulvovaginal candidiasis.
Efinaconazole: onychomycosis.
Ketoconozole: dermatophytosis, candidiasis and shampoo/foam for seborrheic dermatitis.
What are the MOAs and indication for the following antifungals?
Ciclopirox Terbinafine Tolnaftate Nystatin Amphotericin B
Ciclopirox: disrupts macromolecular synthesis; dermatophytes (Candida and Malassezia).
Terbinafine: inhibition of squalene epoxidase (needed for ergosterol synthesis); dermatophytes.
Tolnaftate: unknown, but distorts hyphae and stunts mycelial growth; various dermatophytes and malessezia (not Candida).
Nystatin: alters membrane permeability; mucosal and cutaneous Candida.
Amphotericin B: alters membrane permeability; cutaneous Candida.