The clear and odourless gel, called Ushercell, developed by Canada-based Polydex Pharmaceuticals, acts in the vagina to prevent sperm reaching their target. Developed over the last decade, with nearly $75m (€52.8m) invested in its R&D, the gel has just completed Phase II trials as a contraceptive with plans underway for Phase III trials.
Studies have so far shown Ushercell to be 96.1 per cent effective as a contraceptive when used as directed - this is compared to the male condom which offers 86 per cent to 97 per cent effectiveness, and the female condom which is 79 per cent to 95 per cent effective in the prevention of pregnancy. Besides its contraceptive indication, several in vitro studies have also shown Ushercell to be effective in inhibiting sexually transmitted infections (STIs) such as gonorrhoea, Chlamydia and herpes I and II, though human trials have so far shown varying degrees of effectiveness, Polydex spokeswoman Linda Hughes told in-PharmaTechnologist.com.
The active ingredient in Ushercell is a special form of cellulose sulphate that when mixed with water and preservatives it generates a gel with a thick viscosity. The gel, which is not absorbed by the body - it breaks down naturally and is discharged - acts by inhibiting hyaluronidase. This enzyme is released by sperm to aid conception, and the gel is thought to both immobilise the sperm and impair their penetration of cervical mucus.
Packaged in individual dose applicators, Ushercell can be applied up to 18 hours before sexual intercourse and had been found to completely block conception when applied 15 minutes prior to insemination with sperm, Hughes said. All trials have assumed one application per act and have shown safe use four times a day. "Because it is not absorbed in the body, it does not have the side effects of hormonal contraceptives. It is dose-dependent and therefore not a regime. It does not have the inconvenience of the condom or other device options. It is clear and odourless, providing discretion. It is likely to be inexpensive. It is natural and is not cytotoxic and therefore results in less irritation than currently marketed lubricant products," Hughes said when asked about the advantages.
Further development of the compound for other uses has also been considered by Polydex. "Potentially, it could be considered in further microbicide development for the prevention of HIV and other STIs as a combination compound," Hughes said.
There was also potential to use Ushercell as a drug delivery system for the treatment of cervical cancer or for the delivery of vaccines, she said. If eventually approved, Ushercell would be competing in a contraceptive market worth $6.7bn (€4.7bn).
However, Ushercell is just one of many novel contraceptives currently being developed. Australian firm Acrux has developed a transdermal spray with a combination contraceptive formulation which is currently in Phase I trials.
Research and development into men's contraceptives for reducing fertility and alternatives to vasectomy are ongoing, meanwhile the Germany-based Institute for Condom Consultancy is developing a spray on condom where the man inserts his penis into a special spray can and pushes a button and is coated in a rubber condom for a one-size-fits-all approach. Trying to break into the same market is Bristol Myers Squibb (BMS) and Warner Chilcott with their Femcon Fe tablets. These spearmint-flavoured chewable contraceptive pills are based on the company's Ovcon 35 (norethindrone and ethinyl estradiol), which has been on the market for around three decades. Meanwhile, Wyeth received US approval earlier this year for the contraceptive pill Lybrel (levonorgestrel and ethinyl estradiol), which taken every day not only prevents pregnancy but stops monthly menstruation.
Even if Ushercell does not gain approval as a contraceptive, Hughes said studies have shown that women in the trials have reportedly found the lubricant quality of Ushercell to be pleasure enhancing.