This disclosure pertains to new compositions and methods comprising a first serotonergic drug and a second serotonergic drug. In one embodiment, the compositions disclosed herein are used for a method of regulating a neurotransmitter receptor, e.g., a serotonin receptor. In one embodiment, the compositions disclosed herein comprise purified compounds, e.g., a purified psilocybin derivative, a purified cannabinoid, a purified terpene, a purified tryptamine, purified LSD, and/or purified MDMA.