I don't have to look at wikipedia to suspect -- that a biological venom will not have a simple formula like that. Well, maybe there are examples from say the bombadier beetle, but a chemical stored in a vertebrate's glands is most likely going to be a complex protein ...
*[EDIT]*
Yep, a mixture of several neurotoxins and hematoxins, including the one you named ...
http://en.wikipedia.org/wiki/Calciseptine ... a calcium channel blocker