← All decks
Dermatology
1. Skin Barrier
Built from Dermatology, 5th Edition
What’s inside
8 sections · 76 slides
Overview
- What this topic covers
Structural Basis for the Permeability Barrier
Why skin needs a barrier, and the bricks-and-mortar model
- Two jobs of the skin barrier
- The bricks-and-mortar model
- Filaggrin and keratohyalin
- Lamellar bodies
Stratum Corneum Formation and Organization
How the barrier is built, layer by layer
- Layers of the epidermis
- Features of the stratum corneum
- Structural basis of low water permeability
- Factors affecting how stratum corneum lipids mediate barrier function
- The stratum corneum reservoir
- The three key stratum corneum lipids
- Ceramides and essential fatty acids
Epidermal Metabolism and the Skin Barrier
How keratinocytes make, secrete and process barrier lipids
- Lipid synthesis during differentiation
- The cutaneous stress test
- Synthetic pathways for the three key lipids
- Lamellar body secretion
- Extracellular lipid processing
- Three hydrolysis reactions that build the barrier
- When lipid-processing enzymes fail
- Desquamation - shedding the outer cells
- Two-compartment system and the pore pathway
- Antimicrobial peptides and the barrier
- Acidification - the acid mantle
- Why acid pH matters for the barrier
Cutaneous Diseases and Barrier Dysfunction
Causes of barrier failure, and the two-way link with inflammation
- Causes of barrier dysfunction
- Genetic disorders of the barrier
- Impact of reduced filaggrin
- Outside-in versus inside-out disease
- How inflammation breaks the barrier
- Barrier dysfunction and systemic disease
Treatment of Skin Barrier Dysfunction
Emollients, occlusion, and lipid-targeted therapy
- Emollients and occlusive dressings
- Emerging and targeted therapies
Transdermal and Topical Drug Delivery
How the same barrier is exploited, and overcome, to deliver drugs
- Topical versus transdermal delivery
- Fick's law of drug absorption
- The vehicle changes drug potency
- Effect of vehicle on corticosteroid potency
- Effect of vehicle on corticosteroid potency (continued)
- Drug concentration is not everything
- Lidocaine absorption and DMSO
- Regional variation in skin permeability
- Why deliver drugs through skin
- Theoretical advantages of transdermal drug delivery
- Steady levels versus repeated dosing
- Conventional transdermal drug delivery using patches
- Limits of a simple patch
Strategies to Enhance Transdermal Drug Delivery
Chemical and physical methods to get more drugs through skin
- Strategies to enhance transdermal drug delivery
- Physical strategies to enhance transdermal drug delivery
- Four pathways into the skin
- Chemical enhancers: how they work
- Water, solvents and surfactants
- Liposomes and nanoparticles
- The stratum corneum reservoir, in cross-section
- Iontophoresis and electroporation
- Ultrasound-assisted delivery
- Micron-scale routes into skin
- Microneedles
- Microneedle vaccination
- Microneedles beyond drug delivery
- Chemical versus physical enhancement
- Key takeaways
- References
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- References (continued)
- Dermatology, 5th Edition (2-Volume Set)