Disposition of [14C]nonoxynol-9 after intravenous or vaginal administration to female Sprague-Dawley rats.

The disposition of nonoxynol-9 labeled with carbon-14 at the ethylene oxide units was studied following an iv or vaginal administration to female Sprague-Dawley rats. The results from the vaginal administration studies indicate 12.8% absorption of 14C radioactivity in 6.0 hr and 37.7% in 24.0 hr. Tissue distribution studies showed that the small and large intestines, including their contents, had the highest 14C activity by either route of administration. Radiomonitored HPLC of bile collected at 6.0 hr and urine at 6.0, 24.0, and 48.0 hr following an iv injection of [14C]nonoxynol-9 showed that the compound was completely metabolized in the body of the rat. The metabolites were primarily excreted in the feces and secondarily in the urine. Analysis of urinary metabolites containing the carbon-14 label, 6.0 hr following an iv dose, indicated the presence of highly polar neutral (53.27%) and acidic (39.23%) species.