Transdermal Drug Delivery Flashcards
transdermal drug delivery system
systemic effects
target is not the skin
TDDs bypass
first pass effect
type of administration of TDDs
controlled and constant
in TDDs, drugs that require high doses
cannot be administered
maximum daily dose of transdermal drugs
10mg or less
solubility of drugs need to be
adequate in both lipophilic and aqueous environments
aqueous solubility of TDDs
over 1 mg/ml
lipophilicity of TDDs
logP (1-3)
molecular size of TDDs
under 500 daltons
drugs at or near saturation will have ____________________ than those in which the drug is unsaturated
greater penetration
percutaneous absorption is ________________ to the area of application
proportional
Fick’s First Law of Diffusion
goal is to reach steady state
passive diffusion
Jt = PAC
J = DKC/h
the __________________ of transdermal delivery must be increased in order to obtain _________________.
how is this done?
amount and rate
the desired therapeutic effects
permeation enhancers
enhancers increase
drug transport
enhancers equation
J = PC
permeability can be enhanced by
altering the structure of the skin
concentration can be altered by
increasing the solubility of the drug
enhancers increase the drug permeability through the skin causing
reversible damage
damage caused by enhancers
increased drug diffusivity by dissolving lipids or denature skin proteins
non polar and oil soluble enhancers
mineral oil
isopropyl palmitate
lauryl alcohol
polar- water soluble enhancers
PEG
PG
ethanol
water
what is the difference between small animal skin and human skin?
small animals lack sweat glands and have more hair follicles
differences in quantity of lipids present
thickness of SC layer increases with animal size
membrane controlled system
drug permeation is controlled by a polymeric membrane
matrix diffusion controlled system
drug is homogeneously dispersed in a hydrophilic polymer
diffusion from the matrix controls the release rate
microreservoir dissolution controlled system
system microscopic spheres of drug reservoir and dispensed in polymer matrix
adhesive dispersion type system
lacks the polymer membrane
drug is dispersed into an adhesive polymer
electroporation
short, high voltage pulses
magnetophoresis
magnetic field
iontophoresis
weak, continuous electrical current
microneedles
sharp micro projections, frequently in patch form
ultrasound
low intensity
