Abstract

PIP: Vaginal spermicides, which were made of many different compounds prior to the 1960s, are today based on a few active principles only. Nonoxynol 9 is the most widely used of these safe and effective surfactants. Methods of evaluation of spermicides are all based on measurement of the time and dose levels necessary to achieve immobilization of sperm under specific conditions. Studies of the mode of action of nonoxynol 9 suggest that the spermicide causes major alterations of the surface membranes and in the organites. To determine whether nonoxynol 9 merely immobilizes or also kills sperm, specimens were collected from 21 donors after 3-5 days of abstinence. The sperm sample characteristics were compared with those of men of proven fertility to ensure that the sperm had fertile characteristics. 8 of the 21 donors were of proven fertility. Criteria for judging the effect of nonoxynol 9 included sperm mobility before and after nonoxynol 9 administration and percentage of live sperm before and after nonoxynol 9 administration. The technique for demonstrating whether sperm are still alive after coming in contact with nonoxynol 9 requires about 30 seconds to 1 minute for completion, so it cannot be stated that immobilization and death of the sperm are instantaneous. The quantities of nonoxynol 9 used were about 1/10 of those used in spermicide contraceptives. The dosage corresponded to about 10 mg of nonoxynol 9 for an ejaculate, while those of local contraceptives are usually 100 mg. This work demonstrated that the action of nonoxynol 9 was not limited to simple immobilization of sperm, but also involved killing them. The advice to spermicide users to avoid vaginal cleansing for several hours after intercourse should be reevaluated in light of these findings.