Following an initial screening visit, Subjects fulfilling the study inclusion and exclusion criteria will enter a pre-treatment screening phase to permit evaluations to confirm eligibility for inclusion into the study. This screening phase will be no longer than 30 days. At the completion of the screening period, eligible Subjects will be randomized at baseline visit to receive either placebo or final doses of SRX246 of 120 mg twice daily or 160 mg twice daily during the double-blind treatment phase. At baseline, Subjects in the active groups will receive 80 mg twice daily for 2 weeks, then escalate to 120 mg twice daily for 4 weeks. Then one group of Subjects will continue to take 120 mg of SRX246 twice daily for an additional 6 weeks, and the second group of Subjects will increase their dose to 160 mg of SRX246 twice daily for 6 weeks. Total dosing duration is 12 weeks.