Contraceptive efficacy of a novel spermicidal microbicide used with a diaphragm: A randomized controlled trial

Kurt T. Barnhart, Michael J. Rosenberg, H. Trent MacKay, Diana L. Blithe, Jim Higgins, Terri Walsh, Livia Wan, Michael Thomas, Mitchell D Creinin, Carolyn Westhoff, William Schlaff, David F. Archer, Charletta Ayers, Andrew Kaunitz, Sutapa Das, Thomas R. Moench

Research output: Contribution to journalArticlepeer-review

46 Scopus citations


OBJECTIVE: Women need products that protect against both pregnancy and sexually transmitted infections, including human immunodeficiency virus (HIV). The acid buffering gel is a nondetergent spermicide that may provide this dual protection by reinforcing normal vaginal acidity to inactivate both sperm and acid-sensitive sexually transmitted pathogens. The objective of this study was to assess the gel's contraceptive effects, safety, and acceptability. METHODS: We conducted a multicenter, randomized, double-masked, noninferiority study at 11 centers, comparing 621women who used an acid buffering gel plus diaphragm with 300 women who used a nonoxynol-9 spermicide plus diaphragm for 6 months. A double-masked study extension followed 234 women for an additional 6 months of use. RESULTS: The 6-month pregnancy rate per hundred women was 10.1% (95% confidence interval [CI] 7.1-13.1%) for acid buffering gel and 12.3 (95% CI 7.7-16.9) for nonoxynol-9 spermicide users. The difference in rates was -2.2% with a 95% CI -7.7 to 3.3%. Consistent and correct use 6-month pregnancy rates were 4.7% for acid buffering gel and 6.1% for nonoxynol-9 spermicide users, calculated from those cycles where diary entries indicated such use. Adverse events and acceptability were similar between the two groups. Pregnancy probabilities were similar between groups participating in the 12-month study extension. CONCLUSION: An acid buffering gel used with a diaphragm is a safe, acceptable contraceptive with efficacy comparable to that of a common commercial spermicide with diaphragm. CLINICAL TRIAL REGISTRATION:,, NCT00065858 LEVEL OF EVIDENCE: I.

Original languageEnglish (US)
Pages (from-to)577-586
Number of pages10
JournalObstetrics and Gynecology
Issue number3
StatePublished - Sep 2007
Externally publishedYes

ASJC Scopus subject areas

  • Obstetrics and Gynecology


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