Efficacy, safety and acceptability of a benzalkonium chloride spermicide cream in women aged 40 years and over needing contraception: A prospective multicentre study

Objective: This multicenter prospective study (BZK40+) aims to determine the efficacy and tolerance of a benzalkonium chloride-containing spermicide as contraceptive among women aged 40 and over.

Procedure: Fertile women enrolled in this open single-arm study were instructed to systematically use the benzalkonium chloride spermicide before each intercourse. At the end of a 6-month mandatory period, participants were given the option of continuing the study for a further 6 months. The primary endpoint for contraceptive efficacy was the Pearl Index (PI) up to 12 months of typical use.

Main findings: A total of 151 women (mean age: 45.9 years) were enrolled, 144 (95.4%) completed the initial 6-month period and 63 (41.7%) completed the optional 6-month period. The median number of intercourses ranged from 3 to 5 per month. The spermicide was applied before 96.3% of the 5,895 sexual intercourses. The PI up to 12 months of typical use was 0 pregnancies (95% confidence interval: 0-2.88). The cumulative treatment exposure was 1249.7 women-months.

Conclusion: This first study in women aged 40 years and over shows that benzalkonium chloride spermicide (Pharmatex®) is effective, well tolerated and well accepted in this population. Although very interesting, these results with a PI equal to zero are surprising and not in accordance with the low efficacy of spermicides in the overall population according to the WHO. So, our results should be interpreted with caution and confirmed by future research. Clinical trial registration number (EudraCT): 2016-004,188-38.