A novel psychedelic 5-HT2A receptor agonist GM-2505: The pharmacokinetic, safety, and pharmacodynamic profile from a randomized trial healthy volunteer.

BACKGROUND

The treatment of major depressive disorder (MDD) with available antidepressant drugs is characterized by considerable ineffectiveness. Classical psychedelics such as psilocybin and N,N-dimethyltryptamine (DMT), which act primarily as 5-hydroxytryptamine 2A (5-HT2A) receptor agonists, have shown preliminary efficacy for inducing long-term remission in MDD after one or two doses. GM-2505 is a novel, 5-HT2A receptor agonist, developed for treating MDD.

METHODS

In this single-ascending dose, randomized, placebo-controlled, double-blind study, we characterized GM-2505's safety, tolerability, pharmacokinetics (PK), and pharmacodynamic (PD) profile in 48 healthy participants.

RESULTS

Single intravenous (IV) doses up to 20 mg demonstrated an acceptable safety profile of mild transient adverse events, short-term, non-clinically significant increases in blood pressure and pulse, and no significant changes in electrocardiographs, consistent with other 5-HT2A receptor agonists. In general, GM-2505 Cmax and AUClast increased dose proportionally, with t1/2 of 40-50 minutes. Generally, dose-dependent effects were observed for neuroendocrine hormones, several neuropsychological and neurophysiological measures, and subjective drug effects. Dose-related effects were also observed in resting-state electroencephalography (rsEEG), with decreased power in the low frequency rsEEG bands (theta and alpha), and increased in the high frequency bands (slow and fast gamma).

CONCLUSIONS

These PD findings were similar in nature and magnitude to other 5-HT2A receptor agonists that have been studied clinically. In line with the GM-2505 PK profile, the duration of cardiovascular and subjective effects was shorter than psilocybin but longer than DMT, demonstrating a potentially more practical temporal profile for use in a supervised clinical setting compared to longer-acting 5-HT2A receptor agonists, with an optimal dose range of 10-15 mg IV. Clinical trial (ISRCTN64428072) registration: https://www.isrctn.com/ISRCTN64428072.