Studies of nonoxynol-9. I. The effect on the vaginas of rabbits and rats.

A standard rabbit vaginal irritation test was used to evaluate the morphologic reaction to an aqueous solution of a nonionic spermicidal detergent, nonoxynol-9 (N-9). Various amounts of N-9, between 2.5 mg and 50 mg, were incorporated into cylindrical collagen sponges which were retained in the vagina for 10 days. Changes in the continuity of the epithelial lining, edema of the submucosal layer, and the inflammatory cell infiltrate of this layer were proportional to the amount of N-9 tested. An increase in semiquantitative score for the inflammatory changes in the vagina was noted for increasing amounts of N-9. In young adult female rats treated vaginally with 5 mg/100 gm body weight/day of aqueous N-9 for 5 to 20 days, the number of cells (DNA) was significantly increased on day 5. The collagen content in the vaginal wall (hydroxyproline) was significantly increased after 15 and 20 daily injections of the detergent. We conclude that both morphologic and chemical changes in the vagina are compatible with the inflammatory reaction induced by the detergent tested.