Bay 41-8543 is a soluble guanylate cyclase (sGC) stimulator developed primarily for the treatment of pulmonary arterial hypertension (PAH). It enhances the activity of sGC, an enzyme involved in the nitric oxide (NO) signaling pathway, which leads to increased production of cyclic guanosine monophosphate (cGMP). Elevated cGMP levels promote relaxation of vascular smooth muscle, resulting in vasodilation and reduced pulmonary vascular resistance.

This compound has shown potential in improving cardiac output and exercise capacity in preclinical models of PAH. Its mechanism of action is independent of endogenous NO, making it beneficial even in conditions where NO bioavailability is reduced. Due to its targeted effect on the pulmonary circulation, Bay 41-8543 has been investigated as a therapeutic agent to delay disease progression and improve quality of life in patients with chronic pulmonary hypertension. Although it did not advance to widespread clinical use, it served as an important pharmacological tool in understanding sGC modulation and informed the development of related therapies.