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62 Cards in this Set
- Front
- Back
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Two types of dermatological products applied to skin
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medicated
non-medicated |
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Non-medicated (cosmetics)
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protective, moisturizing, emollient (soften or soothe the surface of the skin)
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Medicated (treatment of skin conditions)
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bacterial, fungal, viral infections, corns, warts, and contact dermatitis (eczema)
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formulations of dermatological products
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ointments, creams, gels
(for external use only) |
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Advantages of dermatological products (three things)
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-High drug concentration at site of application
-Low risk of systemic side effects -Non-invasive; easy to use |
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Disadvantages of dermatological products (five things)
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-Contact time for drug is limited
-Patients find ointments and creams are messy to use -A small amount of drug can be absorbed systemically -Formulations can cause skin irritation -A specialized packaging system is needed to measure and apply an exact dose |
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Skin problems affecting the stratum corneum
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Psoriasis: hyper-proliferative thickening
Chapped skin (lips): extremely dried out, brittle |
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Skin problems affecting the viable epidermis
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Eczema (itching): cell damage and inflammation
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Skin problems affecting the dermal-epidermal interface
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Warts: overgrowth of the basement membrane
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Skin problems affecting the dermis
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scarring: overgrowth of fibroblasts
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Skin problems affecting the hair follicles
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Hirsutism: hyperactivity
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Skin problems affecting the sebaceous glands
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Acne: occlusion
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Skin problems affecting the eccrine sweat glands
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Heat rash: inflammation
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Fungal infections
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athlete's foot, ringworm
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Antipruritics
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Relieve itching of skin, e.g. menthol, phenol, camphor, coal tar, calamine, antihistamines.
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Keratolytics
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Remove or soften the thickened or scaly stratum corneum, e.g. 4-10% salicylic acid.
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Antieczematous agents
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Assist in removal and treatment of oozing and vesicular excretions, e.g. boric acid solution, 2-5% coal tar solution, various antiseptics.
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Antiparasitics
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Destroy or inhibit living infestations, e.g. 10-30% benzoate, sulfur.
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Antiseptics and antibiotics
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Bateriostatic, bactericidal, fungistatic, fungicidal, e.g. 1-5% iodine, chloramphenicol, neomycin.
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Antiseborrheics
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Reduce discharge from sebaceous glands and remove symptoms, e.g. antipruritics, resorcinol.
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Emollients
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Soften or soothe the surface of skin, e.g. cold cream.
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Protectives
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Protect the skin from moisture loss and chemicals, e.g. petrolatum, zinc oxide, silicones.
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Oil-in-water
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Hydrophilic ointment
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Water-in-oil
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Eucerin
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Hydrocarbon
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White Petrolatum (Vaseline)
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Anhydrous absorption
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Aquaphor
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Characteristics of an ointment
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Has a translucent appearance, thick, somewhat occlusive, greasy, excellent for emollient effects
-Not for moist lesions |
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Types of bases for an ointment
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-hydrocarbon (petrolatum, beeswax): C16-C30 + C30-C50
-vegetable oils (do not allow inclusion of water) -fatty alcohols (allow inclusion of limited amount of water) -water-soluble base (polyethylene glycol) non-greasy, poor occlusive |
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Characteristics of creams
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Emulsions of oleaginous substances and water
-Can be used for "weeping" wounds -Spread more easily over skin than ointments |
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Types of creams
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-oil-in-water: not water washable, absorb limited amounts of water
-water-in-oil: water washable, absorb some water, contain surfactants |
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Characteristics of gels
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-Three dimensional networks of inorganic molecules (aluminum hydroxide) and large organic molecules (carbomer) in a liquid (thixotropic).
-Sols or gels -Drug is dispersed or dissolved in water or a water/ethanol mixture in the gel. |
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Pros of gels
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-water-washable
-clear (patients like this) |
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Characteristics of pastes
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-A larger proportion of solid material than ointment.
-Less greasy than ointment (use less amount of base); zinc oxide paste. -Pastes are stiffer than ointments |
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Pros of pastes
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-Less greasy than ointment (because they use less base); zinc oxide paste
-Good for absorption of secretions (starch) |
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Cons of pastes
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-Not good for applying to hairy areas
-Not water washable |
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Vehicle effects of hydrophobic vehicles (affect the skin)
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Enhanced percutaneous drug absorption due to opening up of intra- and inter-cellular channels by hydration of the stratum corneum and increase dissolution of the drug
-Examples: ointments with a lot of oleaginous substances, w/o creams. |
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Vehicle effects of relatively hydrophilic products
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Increase drug solubility and diffusion from a vehicle
-Examples: gels, creams (o/w), water soluble ointments |
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Greasy products (w/o cream and ointments)
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-preferred for dry skin and chapped skin
-difficult to wash off and may stain clothing -good for the drug that is desired to penetrate into deeper skin layers due to hydration effect |
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Creams
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Excellent emollient effect and better spreadability (normal skin, humid conditions)
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Gels
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Have faster drug release compared to ointments and creams. Useful for immediate local effect.
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Temperature and lotions and creams
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Relatively unstable to heat and temperature
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Disadvantages of hydrocarbon ointment bases
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-will not absorb water
-greasy -insoluble in water -not water washable -anhydrous |
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Advantages of hydrocarbon bases
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-emollient
-occlusive -inexpensive, non-reactive, non-irritating -insoluble in water -not water washable -anhydrous |
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Examples of hydrocarbon bases
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White Petrolatum
White Ointment Vegetable shortening Vaseline |
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Examples of anhydrous bases
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Lanolin
Aquaphor® Aquabase® Polysorb® Hydrophilic Petrolatum |
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Disadvantages of anhydrous (absorption) bases
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-greasy
-may be sensitizing or sticky (if contain wool wax or wool wax alcohols) -may have compatibility problems (if have soap-type emulsifiers) -insoluble in water -not water washable -anhydrous |
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Advantages of anhydrous (absorption) bases
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-can absorb water
-emollient -occlusive -insoluble in water -not water washable -anhydrous |
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Advantages of Water-in-Oil Emulsion Absorption
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-can absorb water
-emollient -occlusive -insoluble in water -not water washable -contains water |
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Disadvantages of Water-in-Oil Emulsion Absorption
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-greasy
-may be sensitizing or sticky (if contain wool wax or wool wax alcohols) -may have compatibility problems (if have soap-type emulsifiers) -may have stability problems due to water -insoluble in water -not water washable -contains water |
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Examples of Water-in-Oil Emulsion Absorption
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Hydrous Lanolin
Cold Cream Eucerin® Hydrocream® Rose Water Ointment® |
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Examples of Water-Removable (Oil-in-Water Emulsion)
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Vanishing Cream
Dermabase® Velvachol® Unibase® Hydrophilic Ointment |
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Advantages of water-removable (oil-in-water emulsion)
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-can absorb water
-less greasy -insoluble in water -water-washable -contains water |
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Disadvantages of water-removable (oil-in-water emulsion)
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-less emollient
-non-occlusive -may have compatability issues with soap-type emulsifiers -may have stability or microbial problems -may dry out if exposed to air -insoluble in water -water washable -contains water |
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Permeability of drug correlates with three things
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Drug's
-molecular weight -water solubility -oil in water partition coefficient |
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Transdermal systems are useful for:
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Drugs with
-low dose requirement -high skin permeability |
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Principle barrier to transdermal systems
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stratum corneum
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Why do we use transdermal systems?
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-Bypass first-pass effect (e.g. estradiol)
-Reduce side effects by more controlled release -Reduced inter- and intra-patient variability -Increase patient compliance with fewer dosing events- self-administration -Easy to apply and remove |
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Marketed transdermal products
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-Scopolamine (anti-nausea)
-Nitroglycerine (angina) -Clonidine (hypertension) -Fentanyl (analgesic) -Testosterone (cancer) -Nicotine (smoking cessation) -Estradiol (post-menapausal conditions) -Ethinyl estradiol/norelgestromin (contraception) |
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Disadvantages of transdermal delivery systems
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-Lipophilic (moderately) drugs with low Mw only
-Potent drugs only (< 10 mg/day) -Drugs with short half-lives only -Atopic dermatitis at the site of application is possible (by the drug or adhesive) -Lag-time to reach steady state (2-6 hrs in some cases) -Skin damage due to adhesion (elderly) -Expensive -Excess drug content in patches (proper disposal) |
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Types of transdermal delivery systems
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-Adhesive patches (SC regulates drug absorption)
-Reservoir (membrane) controlled system -Matrix controlled system |
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Skin controlled diffusion (most situations)
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Js = (Ds Km Cveh) / hs
-Cveh drives partitioning into the skin and diffusion is controlled by passage through the skin - Release is much greater than permeation |
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Device controlled diffusion
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Js = (Dv Cveh) / hveh
-Cveh drives diffusion through the device and releases drug slowly - Permeation much greater than release |
