Psychopharmacology studies a wide range of constituents focusing primarily on the chemical interactions with the brain.  Psychopharmacology is a subfield of pharmacology that deals with chemical signalling and Psychopharmacological substances. Chemical signalling is occurred between neurotransmitters and hormones. Psychopharmacological substances are alcohol, antidepressants, antipsychotics, benzodiazepines, hallucinogens, hypnotics, cannabis and the cannabinoids, opioids and stimulants.

Neuropharmacology is the study of drugs affects on cellular function and mechanisms of the nervous system which they influence behaviour. Molecular Neuropharmacology and Behavioral neuropharmacology are major categories of neuropharmacology. GABA, Dopamine, Serotonin, Ion channels are the neurotransmitters studied under molecular neuropharmacology. The addictive property of Ethanol is studied under Behavioral neuropharmacology.

Psychopharmacology is study about chemicals involves in changes in consciousness and behavior. Neuropsychopharmacology deals with drug-induced changes in the functioning of cells in the nervous system.