In Europe, silibinin is the drug of choice for amatoxin mushroom poisoning, but pharmaceutical grade silibinin is unavailable in North America. What widely available immunosuppressive drug (used to prevent organ transplant rejection) may treat or prevent hepatotoxicity caused by amatoxins?
Cyclosporine.
Cyclosporine is a potent inhibitor of Organic Anion Transporting Protein (OATP) 1B3 needed for alpha-amanitin (amatoxin) to enter hepatocytes. Cell culture studies of human hepatocytes found that cyclosporine prevented intracellular accumulation of alpha-amanitin and maintained cell viability in the presence of higher concentrations of alpha-amanitin.
The authors report a case series of 3 patients with laboratory-confirmed ingestion of amatoxin-containing mushrooms (Amanita virosa in one, Lepiota spp. in two). All received IV cyclosporine for 2 to 4 days and recovered well.
Mackenzie CA, Austin E, Thompson M, Tirona RG. Cyclosporine as a novel treatment for amatoxin-containing mushroom poisoning: a case series. Toxicology Communications 2022; 6:23-27. https://doi.org/10.1080/24734306.2021.2006957
Contributed by: Michael Mullins, MD