4_3TopTransderm2 Flashcards
(41 cards)
At what Km is Pe best?
10^0.3
Describe how Pe is related to Kow.
high Pe directly correlates with Kow up to a point
What factors does the Potts and Guy Equation evaluate?
MW and Kow
What factors does the Abraham Equation take into account?
H-donating ability; H-accepting ability; hydrophobic area
Describe the relative importance of MW and Kow.
Kow more important than MW
Describe the relative importance of H-donating, hydrophobic region and H-accepting abilities.
accepting > V > donating
With what does the hydrophobic region of a drug correlate?
Pe
With what does the MW of a drug correlate?
diffusivity
What is the purpose of the Hadgraft and Pugh Equation?
compares functional groups’ relative contributions to Pe
Why is a ceramide headgroup so polar?
3 OH and 1 amide
What are the 3 general methods for enhancing transport rate?
1) prodrug; 2) permeation-enhanced vehicle modification; 3) solubility-enhanced vehicle modification
What functions are most commonly added with prodrugs?
esters
What factors beside MW affect diffusivity for a prodrug?
1) solubility, 2) enzyme affinity for prodrug
Why are prodrugs beneficial in transport?
decrease H-bonding and increase Kow
What are the 3 methods for permeation-enhanced vehicle modification?
1) occlusive dressings; 2) surfactants; 3) high concentration organic co-solvents
What are the disadvantages to permeation-enhanced vehicle modification?
1) irritation; 2) inter-subject variability; 3) animal models (source of data) more sensitive than humans
How do surfactants work?
disrupt H-bonding or lipid chain packing
What are ADRs for surfactants?
irritation
How does the special co-solvent DMSO work?
solvates lipid polar heads in aqueous region
How does the special co-solvent azone work?
inserts between lipid chains in lipid region
What are examples of surfactants?
1) DMSO, 2) sodium dodecyl sulfate, 3) oleic acid, 4) azone
How do surfactants differ from co-solvents?
larger alkyl chain and amphiphilic
How do co-solvents work?
1) extract lipid from SC to make porous; 2) swells lipid membranes to decrease viscosity
What are examples of high-concentration organic co-solvents?
1) DMSO, 2) dimethyl formamide, 3) propylene glycol, 4) EtOH, 5) N,N-dimethyl acetamide, 6) N-methyl-2-pyrrolidone; 7) 2-pyrrolidone
