um, forget everything I said about arsenic

[Guest guest]

It seems that different arsenicals have WAY different toxicities to

different organisms. Some of the old organic arsenicals (developed in

the decades around 1900) had no use against spriochetes, and some had

no use against trypanosomes. And some had no use against anything

because they were so toxic to mammals.

So I don't think you can look at the whole class of arsenic-containing

drugs and expect any useful regularity whatsoever.