Today vaginal contraceptive sponge: a technical review.
A new vaginal contraceptive sponge (Today) successfully completed the US Food and Drug Administration NEW DRUG review process for safety and efficacy on April 1, 1983. The Today sponge will be marketed as an over-the-counter drug. The product consists of a resilient, hydrophilic, polyurethane foam sponge impregnated during manufacture with nonoxynol-9 (N-9), a spermicide in use worldwide for over 20 years. N-9 has been classified as safe and effective by the FDA Advisory Review Panel on OTC Vaginal Contraceptives. Contraception with the Today sponge occurs by: 1) spermicidal action of N-9, 2) sperm absorption into the sponge, and 3) blockage of the cervix. The principal advantage of the Today contraceptive sponge, aside from being available without prescription, is that it separates the act of contraception from that of intercourse, thus permitting for the 1st time, sexual spontaneity with a vaginal contraceptive. Multiple coital episodes are possible with a single sponge. Preclinical USP toxicity studies, mutagenicity assays, allergenic response tests, microbiological studies, and human clinical trials conclusively show no evidence of a significant health risk. The product was found in laboratory tests to be hostile to the growth of Staphylococcus aureas, suspected in the etiology of Toxic Shock Syndrome (TSS). Clinical trials with the Today contraceptive sponge, however, were not large enough to assess the risk of developing TSS. Particular attention has been directed to demonstrating safety with respect to carcinogenicity and mutagenicity. Assays for monomers have continually shown the finished product sponge and the polymeric sponge alone to lack any concerns in this area. These assays are conducted on a continuing basis through a formal stability program now in its 3rd year. This stability program includes accelerated testing at both high and low temperatures for up to 3 months, which has confirmed a lack of product degradation. Further, and most significantly, the product has been subjected to a stringent series of carcinogenicity and mutagenicity screens consisting of both the Ames Salmonella Mutagenicity Test and the Mouse Lymphoma Forward Mutation Assay. These tests have been conducted by both Huntingdon Research Center and Litton Bionetics, and have been successfully passed by the Today sponge in every instance. Phase I trials beginning in 1977 (100 women) demonstrated general acceptability and led to improvements in contraceptive capability. Phase 2 clinical trials beginning in 1978 (400 women) produced a cumulative 6-month life-table pregnancy rate of 5.98/100 women; the protocol called for 1 month use of a single sponge with reuse/washing permitted for a maximum of 10 washings. Phase 3 randomized comparative trials (1600 women) began in 1979 and are ongoing internationally and in the US. This protocol calls for a single sponge use for up to 48 hours wear time. Data to date indicate that sponge effectiveness is in the same range as other vaginal contraceptives. Analysis of the outcome of pregnancies during and after use of the sponge indicates no teratologic or embryologic effects. Of the 719 women in the US studies, 1.7% discontinued because of itching, irritation, rash; 1.9% discontinued because of allergic reactions. These results are consistent with the normal allergenic reactions experienced with the use of N-9. Since insufficient numbers of women in the Phase 3 studies chose to use the sponge for a full 48 hour period, statistical analysis of effectiveness data permits only a single day use recommendation. Thus, in the US, users are instructed to rely on the sponge for pregnancy prevention no longer than 24 hours and to leave the sponge in place at least 6 hours after the last episode of coitus. (author's modified)