The uricosuric effect of oxaprozin in humans.

The effects of oxaprozin, a new investigational propionic acid analogue, and indomethacin on uric acid metabolism were compared in 12 healthy volunteers receiving either agent, first as a single dose and then daily for seven days. While indomethacin did not alter either serum or urinary uric acid values, oxaprozin caused a fall in serum uric acid levels from 5.8 +/- 0.2 mg/dL to 4.8 +/- 0.4 mg/dL (P less than 0.01). Urinary uric acid excretion rose from a baseline of 673 +/- 47 mg to 825 +/- 66 mg/24 h by day 7 of treatment (P less than 0.01). Since oxaprozin was associated with no change in glomerular filtration rate in these studies, the hypouricemic effect of oxaprozin is most likely a result of its direct uricosuric action. Because indomethacin and oxaprozin both are inhibitors of urinary prostaglandin E2 excretion, the data suggest that prostaglandin inhibition per se is not associated with changes in uric acid excretion.