Nomenclature
Symbols
A	age [a]
Apt	active area of the patch [m2]
ci α	drug concentration of substance α in material i [kg m-3]
csc,max α	maximal concentration in the stratum corneum [kg m-3]
cpt,iniα	initial concentration in the patch [kg m-3]
dsc	thickness of stratum corneum [m]
dep	thickness of epidermis [m]
dvep	thickness of viable epidermis [m]
dpt	thickness of patch [m]
Di α	diffusion coefficient/diffusivity of substance α in material i [m2 s-1]
Gbl,up(t)	uptake flow rate in blood at a specific point in time [kg s-1]
Gpt,rel(t)	release flow rate of patch at a specific point in time [kg s-1]
gbl,up(t)	uptake flux across the skin into the blood at a specific point in time [kg m-2 s-1]
KA/B α	partition coefficient between material A and B for substance α
Ko/w α	partition coefficient between octanol and water for substance α
Ki α	drug capacity of substance α in material i [-]
Lpt	length (or width) of patch (reservoir) [m]
Lsk	length (or width) of skin [m]
mpt,ini	initial amount of drugs contained in the patch [kg]
mpt,res(t)	remaining (residual) amount of drugs contained in the patch at a specific point in time [kg]
mep,stor(t)	total amount of drugs stored in the epidermis at a specific point in time [kg]
mpt,rel(t)	cumulative amount of drugs released by the patch at a specific point in time [kg]
mbl,up(t)	cumulative amount of drugs taken up by the blood flow at a specific point in time [kg]
R	diffusive resistance of a material [s m-1]
Ss α	volumetric source term for substance α [kg m-3s-1]
SU,Xj	relative sensitivity of U to a change in Xj
t	time [s]
t1/2	half-uptake-time [s]
U	process quantity
Xj	model input parameter
Ybl,up	fractional drug release of the patch [-]
Greek symbols
α	substance indicator
ψα	drug potential of substance α [kg m-3]
Subscripts
bl	blood
i	material indicator
ini	initial
sc	stratum corneum
ep	epidermis
vep	viable epidermis
ini	initial
fin	final
up	uptake
rel	release
stor	stored
sk	skin
pt	patch
Abbreviations
HUT	half-uptake-time
TDDS	transdermal drug delivery systems