Derm Pharmaco Flashcards
Drugs that decrease cell-to-cell adhesion in the cornified epidermal epithelial cells, facilitating the sloughing of excessive accumulations of cornified cells typical in many dermatological diseases
Keratolytic
Drugs that decrease basal cell proliferation typical in many dermatological diseases. This increased basal cell proliferation contributes to the accumulation of stratum corneum cells
Keratoplastic
Typically oily substances that fill in spaces between corneocytes to improve barrier function and decrease transepidermal water loss in skin
Emollient
Typically oily substances applied to the stratum corneum, forming a water-impermeable barrier that can work to retain hydration from a bath, and also to decrease transepidermal water loss in skin
Occlusive
Hygroscopic (water attracting) substances that “draw” water into the stratum corneum, largely from the dermis, with a smaller contribution from environmental humidity (when it is above 50% humidity)
Humectant
Topical products that emulsify, soften, and break up waxy debris and exudate
Ceruminolytic
Dioctyl sodium sulfosuccinate (water-based detergent) squalene (oil), propylene glycol, glycerin (organic liquids), various oils
Ceruminolytic Drugs
Humectant ceruminolytic, creates foaming action in ear
Carbamide Peroxide
Common in ceruminolytic products. Lactic, salicylic, benzoic, malic acids. Promote lower pH, mildly antibacterial/antifungal, and are keratolytic
Alpha-hydroxy Acids
Keratolytic w/ activity against Staph. pseud. Degreasing agent -> Drying effect. Gel formulation (5-10%) can be very skin irritating for some patients
Benzoyl Peroxide Facts
Strength 2%-4%. Active against Staph. spp. higher % -> more killing (also more drying/irritation). Daily 4% shampoo/solution (3-5 min contact time) as effective as 4 weeks amoxi-clav for Staph. psude., INCLUDING MRSP PATIENTS. Also effective against Malassezia spp. Poor choice for dermatophytes.
Chlorhexidine Facts
Limited veterinary data. Silver-resistant Staph. spp. in human documented
Microsilver Antibacterial Facts
Effective antibacterial w/ minimal skin irritation at 0.05%. Good results in pyoderma patients have been seen diluting regular household bleach (about 6%) from 1:32 to 1:100. ALERT: Commercially available product at 0.01% ineffective in clearing superficial pyoderma.
Sodium Hypochlorite (bleach) Solution Facts
Topical antibacterial targeting Staph. and Strep. spp. Good skin penetration but must be undisturbed 5-10 minutes following application. Resistance can occur when used prophylactically
Mupriocin Facts
Topical antibacterial targeting Pseudomonas spp. effective in humans, limited veterinary data
Silver Sulfadiazine Facts
Available as a dip. Very effective against dermatophytes. Can be used on young patients. Mildly antibacterial, antipruritic, keratolytic, keratoplastic. BUT, potential for extreme drying, it smells bad, and can stain/damage porcelain and can damage gold jewelry.
Lime Sulfur Facts
Topical azole antifungal. Good activity against dermatophytes and Malassezia spp. Generally limited adverse effects. (Note that topical treatment of dermatophytosis is recommended only for limited, focal lesions). Interestingly, miconazole enhances topical bacterial kill from chlorhexidine
Miconazole
Topical azole antifungal. Good activity against dermatophytes and Malassezia spp.
Clotrimazole
10 minutes
Minimal Medical Shampoo Dwell Times
Salivation, tremors, seizures
Pyrethrin toxicity signs
Extracts of chrysanthemum flower. Prolong sodium influx in nerve depolarization -> hyperactivation. Rapidly kills adult fleas, lice, Cheyletiella, and Otodectes. Little residual activity. Generally safe for cats, BUT IMPORTANT TO ONLY USE PRODUCTS APPROVED FOR CATS. Major source of feline toxicity is inappropriate use of canine products (much higher concentration!)
Pyrethrins Facts
Synthesized forms structurally similar to pyrethrins, for example permethrin. Greater residual activity. Slower kill vs. pyrethrins. Cats sensitive to toxicity, SO ONLY USE PRODUCTS APPROVED FOR CATS. Major source of feline toxicity is inappropriate use of canine products (much higher concentration!)
Pyrethroids Facts
Carbamates such as carbaryl are available in sprays, dips, collars, and premise-control sprays, and they are safe for dogs and cats. Toxicity largely overstimulation of parasympathetic nervous system
Carbamates Facts
Example: chlorpyrifos (Dursban, Duratrol). Gradually being discontinued from marketplace due to safety concerns. Most are only approved for dogs.
Organophosphates Facts
Flea adulticide with activity against ticks. Spray, spot-on. Good residual activity after bathing. Can be combined with methoprene to add ovicidal action
Fipronyl (Frontline)
Flea adulticide. Spot-on. Applied 7-30 days, depending on severity. Combination with permethrin adds kill on mosquitos and tics, and adds some mosquito repelling. Combined with moxidectin, adds heartworm prophylaxis, intestinal parasiticide and Otodectes miticide
Imidacloprid (Advantage, K9 Advantix)
Spot-on. Flea adulticide, intestinal parasiticide, Otodectes miticide, heartworm prophylaxis
Selamectin (Revolution)
Oral. Flea adulticide approved for dogs and cats. Main use for this product is the rapid and complete kill of adult fleas. Off-label use for subcutaneous maggot infestation (dogs and cats)
Nitenpyram (Capstar)
Monoamine oxidase inhibitor. The only licensed product approved for generalized demodicosis. FINAL DILUTED SOLUTION SHOULD NOT BE STORED, toxicity increases over time.
Amitraz (Mitaban)
Flea insect growth regulator. Prevent maturation to adults
Methoprene (Ovitrol)
Flea insect growth regulator. Prevent maturation to adults
Pyriproxifen (Nylar)
Impairs ability to form exoskeleton in developing fleas (no effect on adults). Cat product higher concentration than dog due to lower feline oral bioavailability
Lufeneron (Program)
Topical antipruritic. Mechanism unknown, effect may persist for up to 72 hrs. ALERT: Effectiveness researched only in the raw product, scant data on effects once it is processed into shampoos, sprays, lotions.
Colloidal Oatmeal
Topical antipruritic. Mechanism likely due to salicylates in plant liquids
Aloe Vera
Likely reduce pruritis by acting as counter-irritant, or by acting as local anesthetics
Phenol/Menthol
Topical anesthetic. Potential to cause methemoglobinemia
Pramoxine
Anti-pruritic, Anti-inflammatory
Glucocorticoid effects in dermatology
Rank the order of topical glucocorticoid potency (low to high)
Hydrocortisone < Triamcinolone < Betamethasone
Can topicals cause iatrogenic Cushing’s
Yes, especially the more potent ones like betamethasone. Adverse effects range from limited, focal skin changes to (unusually) full-blown Cushing’s even from topical use. Factors include extent of skin coverage
Any dermatosis that involves crust, scale, or lichenification
Indications for anti-seborrheic drugs
Benzoyl peroxide, selenium sulfide, tar, sulfur, salicylic acid
Common anti-seborrheic ingredients
Keratolytic, degreasing, possibly “flushing” debris from hair follicles
Benzoyl peroxide beneficial effects in seborrhea
Keratolytic, keratoplastic, degreasing. Activity against Malassezia. Because of tendency to be extremely drying, reserve for severe cases or use with emollient/humectant. ALERT: DO NOT USE ON CATS
Selenium Sulfide
Keratolytic, keratoplastic. Also antifungal, antibacterial, antipruritic. Often combined with salicylic acid, increased keratolytic activity
Sulfur
Keratolytic, mild bacteriostatic and antipruritic
Salicylic Acid
Good keratoplastic. Because tar contains many carcinogenic chemicals, its continued uses is likely to be short-lived. ALERT: Do not use tar topicals in cats
Tar
Oils, animal fats, fatty acids, ceramides
Examples of Emollients
Paraffin, petrolatum, mineral oil
Examples of occlusives
Lactic acid, urea, glycerin, propylene glycol
Examples of humectants
Essential part of ceramides, which are important in healthy skin structure and function. Currently scant clinical data on effectiveness
Phytosphingosines
Immunomodulator, immunosuppressive, inhibits maturation of T cells. Indications: pruritus, autoimmune skin diseases, perianal fistula
Tacrolimus
Immunomodulator, activates innate immunity. Indications papilloma, herpesvirus lesions.
Imiquimod
