There was found to be 2
optical isomers of epibatidine, and only the (+)-Epibatidine
was secreted by the frogs, whereas on testing,
both enantiomers were discovered to be effective
as painkillers, so the synthesis of a racemate
would not affect activity.
Hundreds and hundreds of molecules structurally
similar to epibatidine started to be tested for
analgesic activity without the side effects of
epibatidine. The article published by Daly in
the prestigious journal, Journal of the American
Chemical Society in 1992 highlighted these discoveries.
One of the newest developments, in 1997, turned
up the molecule ABT-594 which has been shown to
be a powerful analgesic, with very low toxicity.