5-HT	5-Hydroxy Tryptamine or Serotonin
AI	Artificial intelligence
BBB	Blood–brain barrier
CNS	Central nervous system
ICHQ3C(R9)	International Council for Harmonisation guideline Q3C(R9): Impurities—Guideline for Residual Solvents
IM	Intramuscular
ISFDs	In situ-forming depots
IVIVC	In vitro–in vivo correlation
LAI	Long-acting injectable
MAOIs	Monoamine oxidase inhibitors
MDD	Major depressive disorder
ML	Machine learning
NE	Norepinephrine
NIR	Near-infrared
NLCs	Nanostructured lipid carriers
PBPK	Physiologically based pharmacokinetic
PCL	Polycaprolactone
PDE	Permitted daily exposure
PEG	Polyethylene glycol
PLA	Polylactic acid
PLGA	Poly(lactic-co-glycolic acid)
SC	Subcutaneous
SLNs	Solid lipid nanoparticles
SNRIs	Selective serotonin–norepinephrine reuptake inhibitors
SSRIs	Selective serotonin reuptake inhibitors
STARD	Sequenced Treatment Alternatives to Relieve Depression
TCAs	Tricyclic antidepressants
WHO	World Health Organization