Pharmacology Flashcards
What are the 3 main routes of epithelial drug administration?
Topical
Transdermal
Subcutaneous
What is the main barrier to drug absorption through the skin?
Stratum corneum AKA keratin layer
What does the stratum corneum consist of?
Mostly corneocytes surrounded by intercellular lipids
Briefly explain the Brick and Mortar model of the stratum corneum?
The corneocytes (bricks) are held together by corneodesmosomes (rivets) which sit in multiple lamellar strucutres of inter-cellular lipids (Mortar)
How are drugs absorbed across the skin?
By diffusion
What 2 ways do drugs diffuse across the skin?
Majority by the intercellular route and some by the transappendagel route (Hair follicles are sweat glands)
List the types of topical treatment from most to least water?
Lotions Creams Ointments Gels Pastes Powders
How does the lipophilicity of a drug/base affect its topical absorption?
Like is to be with like
So a lipophilic drug is better absorbed in a hydrophilic base and vice versa
The body is lipophillic (generally) so lipophillic drugs are better absorbed
What 3 things must be remembered when prescribing topical treatments?
The concentration
The salt of the drug
The vehicle
What is subcutaneous drug admission?
Given a drug by a needle through the epidermis into the subcutaneous tissues.
What is a depot in reference to subcutaneous drug admission?
Forming a collection of a drug in subcutaneous fat for slow release over time.
What is transdermal drug delivery?
A way of given a drug transdermally over time (e.g a patch)
What 4 things make a drug sutible for transdermal use?
Low molecular weight
Moderately lipophilic
Potent
Relatively brief half-life
To be likely to have a systemic effect when given topically what conditions must a drug and its base have?
The drug must be lipophilic and the base hydrophilic
