Topical Agents Flashcards
What are the layers of the skin from superficial to deep? (5)
Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale
Where does cell division occur within the skin?
Basal layer
Which cells of the skin synthesize epidermal proteins?
Spinous layers
What happens to the cell membrane of skin epithelial cell as they move toward the periphery?
Plasma membrane is replaced by an envelope of insoluble lipid compounds
What happens in the stratum lucidum?
Cell death
Strengthening of the keratin filaments via crosslinking
What are the cells that are a part of the stratum corneum?
Corneocytes (flattened and lipid depleted keratinocytes)
What is the rate limiting step (major barrier) in percutaneous absorption?
Stratum corneum
What are the appendages (shunt routes) through the skin?
Through hair follicles/ sweat glands
What are the two routes that drugs can go through corneocytes?
Intracellularly
Transcellularly
What are the drug “vehicles” for percutaneous drugs?
Inactive part of the preparation that carries the drug
What are the common vehicles for percutaneous drugs?
Ointments
Creams
Gels/foam
Where do you not want to apply ointments?
Areas where skin rubs against skin
What are ointments?
Water in oil emulsion
What are creams?
Oil in water emulsion
What are gels/foams?
Water-soluble emulsion
What types of vehicles are appropriate for intertriginous areas of the body?
Creams
Lotion
Solutions
What are aerosols?
Fine solid or liquid particles dispersed in gas
What type of vehicle is appropriate for the scalp and hairy areas?
Lotions Gels Solutions Foams Aerosols
Where are lotions, gels, solutions, and aerosols useful?
Scalp and hairy areas
Where are creams, lotions and solutions used?
Intertriginous areas
What is the golden rule of dermatology?
If it’s wet, dry it
If it’s dry, wet it
What are the factors that determine the rate of percutaneous absorption? (4)
- Concentration
- Partition of drug from the vehicle
- Diffusion of drug across the skin layer
- Thickness of the stratum corneum
What is the partition coefficient?
Partitioning of the drug from the vehicle into the stratum corneum
What is the drug diffusion coefficient?
Molecule aspect of the drug allowing diffusion across the skin layers
What is Fick’s law?
Determines the rate of drug diffusion across a barrier like the skin
How is concentration of a drug related to the rate of percutaneous absorption?
directly related
How is lipophilicity of a drug related to the rate of percutaneous absorption?
Direct
How is molecular size of a drug related to the rate of percutaneous absorption?
Inversely
How is the stratum corneum thickness related to the rate of percutaneous absorption?
Negative relation
How is cutaneous vasculature related to the rate of percutaneous absorption?
Direct
How is area of absorption surface related to the rate of percutaneous absorption?
Direct
Are mucosal surfaces better or worse at absorbing drugs?
Better
How is the moistness related to the rate of percutaneous absorption?
Direct
How is age of patient related to the rate of percutaneous absorption?
Younger = less total body, and increase SA, leading to increased toxicity