HLP004, or HLP-004, also known as deuterated dimethyltryptamine (dDMT) and formerly as CYB004, is a serotonergic psychedelic related to dimethyltryptamine (DMT) which is under development for the treatment of generalized anxiety disorder. It is administered by inhalation or intravenous injection. The drug is a tryptamine derivative and is a deuterated analogue and form of DMT.
The pharmacodynamic profile of HLP004, including its interactions with serotonin receptors and its effects in animals, is similar to that of DMT. As with DMT, HLP004 is a potent agonist of the serotonin 5-HT<sub>2A</sub> receptor and produces psychedelic-like effects in animals. However, HLP004, due to its deuteration, is more resistant to metabolism than DMT and shows a longer elimination half-life (by 2.5- to 2.9-fold) and slower clearance (by 38 to 55%) in animals. The brain to plasma ratio of HLP004 was also increased (by 30%) relative to DMT, indicating slightly greater central permeability as well.
The pharmacokinetics and effects of HLP004 in humans have been studied and compared with those of DMT. Its elimination half-life was 37 to 40minutes and its duration was approximately 40minutes. For comparison, the half-life of DMT in humans has been reported to be 9 to 12minutes (range 5âÂÂ19minutes). HLP004 produced more robust psychedelic effects than DMT at lower concentrations. Additional details on the pharmacokinetics of HLP004 in humans have also been reported.
The exact chemical structure of HLP004 (i.e., which specific hydrogen atoms have been deuterated) does not yet seem to have been disclosed. However, Helus Pharma (formerly Cybin) patented deuterated tryptamines, including deuterated forms of DMT like DMT-d<sub>10</sub> (decadeutero-DMT; CAS no. 2742678-60-8), in 2023. In addition, DMT-d<sub>10</sub> was given the deudimethyltryptamine in January 2026. Other deuterated drugs related to HLP004 or DMT-d<sub>10</sub> include the deuterated DMT analogue SPL028 (D<sub>2</sub>-DMT; ñ,ñ-dideutero-DMT), the deuterated psilocybin analogue HLP003 (CYB003) (possibly deupsilocin or d<sub>10</sub>-psilocin), and the deuterated phenethylamine HLP005 (CYB005).
As of August 2024, HLP004 is in phase 2 clinical trials for generalized anxiety disorder. It was also under development for the treatment of substance-related disorders and of other psychiatric disorders, but development for these indications was discontinued. The drug is under development by Helus Pharma (formerly Cybin).