PMX 53 is a potent and selective antagonist of the complement C5a receptor (C5aR), making it a valuable tool in modulating inflammatory responses driven by the complement system. It is primarily used in research to investigate conditions involving excessive or dysregulated inflammation, such as autoimmune diseases, sepsis, ischemia-reperfusion injury, and neuroinflammatory disorders like multiple sclerosis and Alzheimer's disease.

Due to its ability to block C5a-mediated immune cell activation—such as neutrophil chemotaxis, cytokine release, and oxidative burst—PMX 53 shows therapeutic potential in reducing tissue damage in acute and chronic inflammatory conditions. It has been studied in animal models of arthritis, colitis, and lung injury, where inhibition of C5a signaling leads to decreased inflammation and improved outcomes.

Its small molecule structure allows for easier delivery and stability compared to biologics, which supports its use in preclinical studies aiming to develop new anti-inflammatory drugs. While not yet a clinical therapeutic, PMX 53 serves as a critical prototype for designing C5aR-targeted treatments.