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.
What is the MOA of Acyclovir?
What is the indication?
Synthetic guanine analog with inhibitory activity.
Treatment of recurrent orolabial HSV-1 and HSV-2 ingections in healthy (non-compromised) adults.
What is the MOA of Capsaicin?
What is the indication?
It binds TRPV1 (a channel in cutaneous nerve fibers), which leads to release of neuropeptides and substance P. It induces lasting desensitization of neurons to a number of stimuli.
Pruritis and chronic pain.
What is the MOA of Salicylic Acid?
What is its indication?
Inhibition of COX.
Pruritis.
What is the drug used for nocturnal pruritis?
Mirtazapine
What is the drug used for cholestatic pruritis?
Sertraline
What is Naltrexone used for? (2)
Cholestatic pruritis
CKD-associated pruritis
What is the drug used for neuropathic pruritis?
Gabapentin/Pregabalin
What are the 2 drugs used for rosacea?
What is their MOA?
Brimonidine: alpha-2 agonist applied as a topical gel.
Oxymetazoline: mixed alpha-1a and alpha-2 agonist applied as a topical cream.
What are the MOAs of the following drugs used to treat ectoparasitic infections?
Malathion
Permethrin
Ivermectin
Lindane
Malathion: organophosphate cholinesterase inhibitor.
Permethrin: binds Na+ channels and blocks membrane repolarization.
Ivermectin: binds glutamate-gated Cl- channels and hyperpolarizes nerve and muscle cells.
Lindane: disrupts GABAergic transmission in insects (highly toxic, so it is only used after other agents fail).
