AGAT	Arginine–glycine amidinotransferase
ALS	Amyotrophic lateral sclerosis
ALSFRS-R	Amyotrophic lateral sclerosis functional rating scale (revised)
AUC	Area under the curve
ATP	Adenosine triphosphate
BBB	Blood–brain barrier
BCRP	Breast cancer resistance protein
CMC	Chemistry, Manufacturing, and Controls
CNS	Central nervous system
CrT	Creatine transporter
CrTD	Creatine transporter deficiency
CSF	Cerebrospinal fluid
DCE	Dodecyl creatine ester
DHA	Docosahexaenoic acid
DTE	Drug targeting efficiency
DTP	Direct NtB percentage
EEG	Electroencephalogram
fMRI	Functional MRI
GAMT	Guanidinoacetate methyltransferase
GLUT	Glucose transporter
GRAS	Generally recognized as safe
GSPR	General safety and performance requirement
iDDC	Integral drug-device combination
IN	Intranasal
IV	Intravenous
LFP	Local field potential
MCT	Monocarboxylate transporter
MDR	Medical device regulation
MRI	Magnetic resonance imaging
MRP	Multidrug resistance-associated protein
NHP	Non-human primate
NOAEL	No observed adverse effect level
NORD	National Organization for Rare Disorders
NtB	Nose-to-brain
NtN	Nose-to-neurons
PBPK	Physiologically based pharmacokinetic modelling
P-gp	P-glycoprotein
PEG	Polyethylene glycol
PSD	Particle size distribution
PET	Positron emission tomography
qEEG	Quantitative EEG
SPECT	Single photon emission computed tomography
WGA	Wheat germ agglutinin