2D	two dimensional
3D	three dimensional
5-HT	5-hydroxytryptamine
ABC	ATP-binding cassette
ADME	absorption, distribution, metabolism, excretion
ANP	atrial natriuretic peptide
ATPase	adenosine triphosphatase
AVP	arginine vasopressin
BBB	blood–brain barrier
BCRP	breast cancer resistance protein
BCSFB	blood–cerebrospinal fluid barrier
CDE	clathrin-dependent endocytosis
CIE	clathrin-independent endocytosis
CMT	carrier-mediated transport
CNS	central nervous system
CP	choroid plexus
CSF	cerebrospinal fluid
EHs	epoxide hydrolases
ESCs	embryonic stem cells
FITC	fluorescein isothiocyanate
FMOs	flavin-containing monooxygenases
FPRL1	formylpeptide receptor-like 1
GSTs	glutathione S-transferases
HTS	high throughput screening
IGF	insulin-like growth factor
IGFR	insulin-like growth factor receptor
iPSCs	induced pluripotent stem cells
IR	insulin receptor
ISF	interstitial fluid
JAMs	junctional adhesion molecules
LDLR	low-density lipoprotein receptor
LLC-PK1	Lilly laboratories culture-porcine kidney 1
LRP	LDLR-related protein
MAGUKs	membrane-associated guanylate kinase-like homologues
MDCK	Madin-Darby canine kidney
MDR	multidrug resistance protein
MMP	matrix metalloproteinase
MPS	Mucopolysaccharidosis
MRP	multidrug resistance-associated protein
NPs	Nanoparticles
NHE	Na+-H+ exchanger
PC	polycarbonate
PCPEC	porcine choroid plexus epithelial cells
PET	polyethylene terephthalate
P-gp	P-glycoprotein
PIOs	2-phenoxy-indan-1-one
PTFE	polytetrafluoroethylene
QAR	quantitative autoradiographic
RMT	receptor-mediated transcytosis
RRCK	Ralph Russ canine kidney
SAR	structure–activity relationships
SLC	solute carrier
TAMARA	tetramethylrhodamine
TEER	transepithelial electrical resistance
TEM	transmission electron microscopy
Tf	transferrin
TfR	transferrin receptor
TJ	tight junction
TTR	transthyretin
UGTs	UDP-glucuronosyltransferases
ZO	Zonula occludens