A phase I comparative study of contraceptive vaginal films containing benzalkonium chloride and nonoxynol-9. Postcoital testing and colposcopy.

ABSTRACT

PIP: Both in vitro and in vivo studies have confirmed the capability of benzalkonium chloride (BZK) to immobilize sperm, protect against sexually transmitted pathogens, and penetrate and thicken cervical mucus. In this Phase I study, 10 US women underwent 2 baseline cycles followed by 3 experimental cycles in which either a new contraceptive vaginal film containing 19 or 25 mg of BZK or a currently marketed film containing 70 mg of nonoxynol-9 (N-9) was used. After a midcycle cervical mucus specimen was analyzed, each woman had intercourse using either no film or a test film and was evaluated 2-3 hours later. The average number of progressively motile sperm seen per high power field was as follows: first baseline cycle, 22.2; second baseline cycle, 22.1; test cycle with film containing 19 mg BZK, 0.2; test cycle with film containing 25 mg BZK, 0.0; and test cycle with film containing 70 mg N-9, 0.0. Colposcopy revealed superficial de-epithelialization without underlying inflammation in 15-20% of baseline cycles, 50% of BZK test cycles, and 69% of cycles in which the N-9 film was used. Women rated both films as neutral or pleasant in terms of appearance, smell, and feel. These findings suggest that contraceptive vaginal films containing either 19 or 25 mg of BZK are as effective as N-9 containing films and may be somewhat less disruptive to the vaginal epithelium. However, since each woman used each BZK film only once, the effects of multiple use on the vaginal epithelium and microflora require further study.