Tinctures are available. But whether they are the "real herb" or some strange substitute, we do not know.
In the meantime, trying to find good information on the web was a lot of fun. Check out this article excerpt:
CHELIDONIUM MAJUS Chistotel. Outstanding hepatic means, patogenez which includes set of the direct and reflex symptoms caused by defeat of this body. Icteric colouring of a skin and especially constant pains under the bottom corner of the right shovel are indications for this preparation. Paralytic extension and a lameness of one finiteness
You can read more of the fun at the source location here.