Stratum Corneum Barrier Properties Quiz

Fick's First Law of Diffusion = Describes the rate of diffusion of a drug through a barrier Topical Bioavailability = The fraction of the drug that reaches systemic circulation after topical application Partition coefficient = The ratio of a drug's solubility in two immiscible solvents Drug transport rate = The speed at which a drug moves across a biological membrane

Stratum corneum layer = The outermost layer of the epidermis, acting as the main barrier to drug penetration Skin surface treatment = Involves the use of cosmetics, sunscreens, and barriers to protect and moisturize the skin Horny layer treatment = Aims to improve emolliency by increasing water content or promoting sloughing Skin appendage treatment = Includes therapies for sweat glands, hair follicles, and other skin appendages

Fick's First Law of Diffusion = Mathematical equation describing the rate of diffusion of a solute across a membrane Topical Bioavailability = The proportion of a drug that enters systemic circulation after topical application Partition coefficient = The ratio of a drug's concentration in two immiscible phases at equilibrium Drug transport rate = The speed at which a drug is transported across a biological barrier

Stratum corneum layer = Outermost layer of the epidermis composed of dead skin cells Epidermis = The top layer of the skin where new skin cells are produced Dermis = The middle layer of the skin containing blood vessels and nerves Appendages (hair follicles, sweat glands) = Structures in the skin that can serve as routes for drug penetration

Intercellular route = Pathway through the spaces between cells in the stratum corneum Transcellular route = Pathway across the cells of the stratum corneum Transappendageal route = Pathway through hair follicles or sweat ducts for drug penetration Follicular route = Pathway specifically through hair follicles for drug absorption

Keratin = Protein component found in corneocytes in the stratum corneum Desmosomes = Cell junctions that hold corneocytes together in the stratum corneum Ceramides, cholesterol, free fatty acids = Lipid components present in intercellular spaces of the stratum corneum Interleukins = Signaling molecules involved in immune responses within the skin

Fick's First Law of Diffusion = Describes the rate of drug transport Partition coefficient = Relates to the drug's distribution between skin and vehicle Stratum corneum layer = The outermost layer of the skin Drug concentration in the applied dermatological preparation = Directly affects the rate of drug transport

High concentration difference (Cv-Cs) = Increases drug transport rate Diffusion coefficient of the drug = Determines the speed of drug transport Surface area of the patch = Affects the amount of drug delivered Thickness of the stratum corneum layer = Impacts the rate of drug permeation

Penetration enhancers = Used to help drugs cross the stratum corneum Pro-drugs = Convert to active form after reaching receptors Transdermal patches = Deliver drugs systemically via percutaneous absorption Topical bioavailability = Concerned with how much of a drug reaches its target site

Many drugs cannot be used topically due to stratum corneum barrier = Requires formulators to use penetration enhancers or pro-drugs Fick's Law governs drug transport across stratum corneum = Describes flux as dependent on concentration gradient and other factors Drug's partition coefficient influences its distribution in skin and vehicle = Determines how much drug stays in each phase Drug concentration in vehicle directly affects transport rate = Higher concentration leads to faster transport through skin