Comparative in vitro study on the local tolerance and efficacy of benzalkonium chloride, myristalkonium chloride and nonoxynol-9 as active principles in vaginal contraceptives.

BACKGROUND: Spermicides have been identified as a potentially attractive alternative to hormonal contraceptives and/or intrauterine devices. Thus, this study aimed evaluating the efficacy and local tolerance of benzalkonium chloride (BKC) and myristalkonium chloride (MKC) contained in Pharmatex® vaginal formulations and compare them with nonoxynol-9 (N-9), the most common active ingredient in topical vaginal contraceptives. METHODS: Human normozoospermic samples were assessed for motility, viability, acrosome status and penetration ability after exposure to control, N-9 or different BKC and MKC doses for 0 and 10 minutes. Local tolerance on HeLa cells was evaluated by the Trypan-blue and MTT assays. RESULTS: Exposure to BKC and MKC reduced acrosome integrity while promoting total immobilisation and complete loss of sperm viability (p < .001, n = 15). Both compounds also compromised sperm penetration ability upon exposure (p < .001, n = 15). N-9 induced the same outcomes (p < .001, n = 15); nevertheless, it was more toxic to HeLa cells than BKC and MKC (p < .05, n = 14). CONCLUSIONS: BKC and MKC present strong in vitro spermicidal activity at lower doses than N-9 and were better tolerated after immediate exposure than N-9. Available Pharmatex® galenic formulations were as effective as products based on N-9.

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.