Science-- there's something for everyone

Friday, December 7, 2012

A new contraceptive

University of Washington researchers, led by Cameron Ball, have invented a new method of contraception. Best of all, their device, made of drug-eluting nanofibers, blocks not only sperm but also sexually transmitted diseases (STDs) like HIV.

Contraceptives and STD preventatives can be classed into two broad categories depending on their mode of action. There are chemical barriers, which can contain hormones, spermicides and/or microbicides. These compounds can be administered as pills, gels, intravaginal rings or vaginal films. There are also physical barriers, the best known of which is the condom. Ideally, a contraceptive would employ both chemical and physical barriers to block sperm and infectious agents. That’s exactly what these new nanofibers do.

The researchers used electrospinning to create their fiber meshes out of materials that are already approved for use in human implants. They used a tampon applicator as a template to ensure easy installation, and incorporated a variety of anti-HIV agents into the finished product. The end result is a soft, flexible object that releases one or more antiviral drugs.

In one of their tests, the scientists incorporated a dye into the fibers and inserted the mesh devices into female mice. Within 30 minutes, the mice’s vaginal tracts were completely coated with dye, indicating that the fibers had indeed released their drug load. When tested in tissue culture experiments, the mesh devices could inhibit both sperm motility and HIV transmission, depending on which drugs they contained. In addition, the fibers present an impenetrable barrier to sperm.

Caption: The electrospun fibers can release chemicals or, as shown here, they can physically block sperm.
Credit: Kim Woodrow, Univ. of Washington.

The invention fulfills the five criteria that Ball and his colleagues set for themselves. The fibers are inexpensive, can deliver multiple drugs, are fully reversible, provide extensive coverage of mucosal tissue and can be managed solely and discreetly by women. This last is important because women can’t always control what their partners are willing to use. 

The next step is to fine-tune the drug delivery system. Different raw materials and thicknesses can determine how quickly the drugs are dissipated throughout the vagina. Thus, it may be possible to create devices for both long term (sustained release) and immediate (quick dispersal) usage, depending on the woman’s needs. And after all, the more choices women have for protecting their health and controlling their fertility, the better.

Cameron Ball, Emily Krogstad, Thanyanan Chaowanachan, & Kim A. Woodrow (2012). Drug-Eluting Fibers for HIV-1 Inhibition and Contraception PloS ONE : doi:10.1371/journal.pone.0049792.