Eton Pharmaceuticals Inc., a spinout from San Diego-based Imprimis Pharmaceuticals Inc., has raised $20 million in a private placement of preferred stock.

The cash comes from an investor syndicate including health-care investors, and members of both Imprimis and Eton’s board of directors.

The spinout will use the money to accelerate its sterile injectible drug candidates, the companies said in a joint statement. After the finding round wraps up, Imprimis will own a 27 percent stake in Eton, along with royalty interest in the two drug candidates.