HLP003, or HLP-003, also known as deuterated psilocybin analogue and formerly as CYB003, is a serotonergic psychedelic related to psilocybin which is under development for the treatment of major depressive disorder, alcoholism, and other psychiatric disorders. It is taken orally. The drug is a tryptamine derivative and is a deuterated analogue of psilocybin and psilocin.