Petasites--Zeller: ZE 339.

The Swiss company Zeller is developing an extract of the plant Petasites hybridus (butterbur) as an antiallergic agent. Petasites hybridus extracts have been known for some time to have therapeutic properties. Zeller's extract is codenamed ZE 339. In in vitro studies, ZE 339 inhibited cysteinyl-leukotriene synthesis in eosinophils and leukotriene B4 synthesis in neutrophils. In mid-2003, ZE 339 was approved, and launched, in Switzerland as Tesalin for the treatment of seasonal allergic rhinitis as a prescription-only product. Tesalin is available as film-coated tablets. Zeller has stated that hepatotoxicity cannot be totally excluded as a possible adverse reaction to Tesalin.