Nitroparacetamol exhibits anti‐inflammatory and anti‐nociceptive activity

Nitroparacetamol (NCX-701) is a newly synthesized nitric oxide-releasing derivative of paracetamol. Following i.p. administration, nitroparacetamol inhibits carrageenan-induced hindpaw oedema formation (ED(50), 169.4 micromol kg(-1)) and mechanical hyperalgesia (ED(50), 156 micromol kg(-1)) in the rat. In contrast, the parent compound, paracetamol, exhibits no significant anti-oedema activity in this model (ED(50)>1986 micromol kg(-1), i.p. ) and is markedly less potent than nitroparacetamol as an inhibitor of carrageenan-mediated hyperalgesia (ED(50), 411.6 micromol kg(-1), i.p.). In a second model of nociception (inhibition of acetic acid induced abdominal constrictions in the mouse), nitroparacetamol administered orally (ED(50), 24.8 micromol kg(-1)), was again considerably more potent than paracetamol (ED(50), 506 micromol kg(-1), p.o.). Thus, compared with paracetamol, nitroparacetamol not only exhibits augmented antinociceptive activity in both rat and mouse but, intriguingly, is also anti-inflammatory over a similar dose range.