Penetration of nabumetone into inflammatory exudates in the rat

The penetration of radioactivity into inflamed sites induced by subcutaneously implanted cotton pellets was studied in the rat after oral administration of [14C]nabumetone. Equilibration between inflamed site and plasma concentrations was slow, maximum concentrations in the pellet granuloma being later than those in the plasma. Nabumetone itself was found only in very low concentrations at the inflamed site and was not found in plasma. The major component (70%) of the radioactivity at both sites was the metabolite 6-methoxy-2-naphthylacetic acid, a compound which has anti-inflammatory properties. Elimination of radioactivity from the plasma and inflamed site was virtually complete within 24 h of dosing. Daily dosing with [14C]nabumetone confirmed that there was no progressive accumulation of radioactivity at the inflamed site.