RO-3 is a potent, and orally active P2X3 and P2X2/3 antagonist with pIC50s of 5.9 and 7.0 for human homomultimeric P2X3 and heteromultimeric P2X2/3 receptors, respectively. It shows selectivity for P2X3 and P2X2/3 over all other functional homomultimeric P2X receptors (IC50 >10 μM at P2X1,2,4,5,7).
- Reduces afferent nerve activity induced by distension or α,β-meATP in guinea pig ureter-afferent nerve and mouse bladder-pelvic nerve preparations.
- Has activity in several rodent models of pain, as well as in cystometry models optimized to measure various parameters associated with sensory regulation of the micturition reflex.
- Exhibits moderate to high metabolic stability in rat and human hepatocytes and liver microsomes, is highly permeable, orally bioavailable (14%), and has a reasonable in vivo plasma half-life (t1/2=0.41 h) in rats.
- Appearance: Solid.
- Color: Yellow to orange.