The non-hallucinogenic LSD analog 2-Br-LSD acts as a partial agonist at several aminergic G protein-coupled receptors, including 5-HT2A, but does not induce the head-twitch response in mice, indicating it lacks hallucinogenic effects. Unlike LSD, 2-Br-LSD does not activate 5-HT2B, avoiding a risk of cardiac valvulopathy. It produces weak 5-HT2A β-arrestin recruitment and internalization in vitro and does not cause tolerance after repeated dosing. In cultured rat cortical neurons, 2-Br-LSD promotes dendritogenesis and spinogenesis, and in mice it increases active coping behavior—an effect blocked by a 5-HT2A antagonist—and reverses behavioral effects of chronic stress. These findings suggest 2-Br-LSD has an improved pharmacological profile over LSD and potential therapeutic value for mood disorders.
A new LSD derivative called 1-valeroyl-LSD (1V-LSD, or "Valerie") has appeared on the online market. It is a higher homolog of earlier derivatives like ALD-52, 1P-LSD, and 1B-LSD. The study analytically characterized 1V-LSD using mass spectrometry, chromatography, NMR, and Raman spectroscopy. In mice, 1V-LSD induced a head-twitch response, a behavioral proxy for human hallucinogenic effects, in a dose-dependent manner. Its median effective dose was 373 nmol/kg, about a third the potency of LSD (ED50 = 132.8 nmol/kg). 1V-LSD likely acts as a prodrug that is hydrolyzed to LSD, but further studies on its biotransformation and receptor pharmacology are needed.