Meclonazepam
Meclonazepam is a benzodiazepine derivative similar in structure to clonazepam. It was first discovered by a team at Hoffmann-La Roche in the 1970s. It has sedative and anxiolytic actions like those of other benzodiazepines, and also has anti-parasitic effects against the parasitic worm Schistosoma mansoni.
Meclonazepam was never used as medicine and instead appeared online as a designer drug.
Pharmacology
Its sedative and anxiolytic abilities are attributed to the same mechanism used by other benzodiazepine drugs: modulation of the GABAA receptor in the brain. This psychoactive activity makes it useful for recreational use. The sedating side effect would also make it unsuitable for routine use as an antiparasitical.Schistosomal parasites do not have an ortholog of the GABAA receptor. Instead, meclonazepam seems to cause a rapid calcium influx, leading to muscle contraction and tegument damage. In 2023, meclonazepam is shown to activate a calcium-permeable schistosome TRP, making this TRP a very likely candidate for its parasite receptor.
Some work has been done to produce two meclonazepam derivatives that show less sedation and more anti-parasite activity in mice. They seem to do this by crossing the blood-brain barrier less readily.