NPPB and heart failure: SG1002 polysulfide—formulated in 200–800 mg capsules twice daily—was safe in both healthy volunteers and patients with heart failure (NYHA II-III); the 21-day treatment stably raised plasma levels of H2S and nitrite, and attenuated the rise in BNP and systolic blood pressure, results that supported its move to larger phase II studies [18].