TL;DR, the identified/named drug that may be repuposed to prevent Zika virus is called Niclosamide, wikipedia has already been updated[1] with its side benefit :)

Nicolsamide is also listed as WHO's "one of the most important medications needed in a basic health system."[1]

There should be more drug repurposing researches to be done but it's probably profit-prohibiting for the big pharmas :(

[1] https://en.wikipedia.org/wiki/Niclosamide