Hypothesis: Pharmacologic inhibition of the sEH enzyme is safe and will result in increased EETs availability at the neurovascular unit, and a measured increase in the EET/DHET ratio in the serum and cerebrospinal fluid. This study is a double-blind, placebo-controlled, phase 1b randomized trial to evaluate the safety and of GSK2256294, an inhibitor of soluble epoxide hydrolase, in patients with aneurysmal SAH.