The following is a summary of “Efficacy, safety and acceptability of a benzalkonium chloride spermicide cream in women aged 40 years and over needing contraception: A prospective multicentre study,” published in the September 2023 issue of Gynecology Obstetrics and Human Reproduction by Serfaty et al.
This prospective multicenter study (BZK40+) wants to find out how well and safely a spermicide with benzalkonium chloride works as a birth control method for women over 40. Fertile women enrolled in this single-arm, open-label study were instructed to use benzalkonium chloride spermicide before each sexual encounter. After the 6-month mandatory participation period, participants had the option of continuing the study for an additional 6 months. The Pearl Index (PI) was the primary endpoint for contraceptive efficacy up to 12 months of typical use.
Among the 151 women enrolled in the study (mean age: 45.9 years), 144 (95.4%) completed the initial 6-month period, and 63 (41.7%) completed the optional 6-month period. The monthly median number of sexual encounters ranged from three to five. The spermicide was administered before 96.3% of the 5,895 sexual encounters. Up to 12 months of typical use, the pregnancy incidence (PI) was 0 (95% CI: 0–2.88). The cumulative exposure to the treatment was 1,249.7 women’s months.
This is the first study to demonstrate that benzalkonium chloride spermicide (Pharmatex®) is efficacious, well tolerated, and well accepted in women aged 40 and older. Although very intriguing, these results with a PI of zero are unexpected and contradict the WHO’s assessment of the low efficacy of spermicides in the general population. Therefore, it is important to interpret the researchers’ findings carefully and wait for further research to confirm them.