Abstract
Naproxen sodium was administered to cynomolgus monkeys (Macaca fascicularis) by oral gavage at daily doses of 44, 88, or 176 mg/kg for 2 wk (2 monkeys/gender) or of 44 mg/kg for 13 wk (4 monkeys/gender). Body weight loss occurred in at least one monkey in all naproxen sodium-dosed groups in the 2-wk (up to 16% loss) and 13-wk (up to 22% loss) studies. Increases in plasma naproxen concentrations were dose proportional between 44 and 88 mg/kg but were less than dose proportional between 88 and 176 mg/kg. Up to 2-fold increases in creatinine and/or serum urea nitrogen values as well as higher renal weights occurred in monkeys receiving 176 mg/kg for 2 wk or 44 mg/kg for 13 wk. Microscopically, renal changes were observed in all naproxen sodium-dosed groups. Renal findings after 2 wk of exposure included increased interstitial ground substance, tubular dilatation, and tubulointerstitial nephritis; in the 13-wk study, cortical tubular atrophy and interstitial fibrosis were also observed. These studies identify the kidney as the target organ of naproxen sodium in cynomolgus monkeys.
