Scientists presented reports on several new vaginal HIV microbicide technologies at the 2010 International Microbicides Conference in Pittsburgh, which ends Tuesday.
A flexible intravaginal ring made of a type of plastic, ethylene-vinyl-acetate copolymer, could be used to deliver HIV drugs to protect women from infection, Andrew Loxley of Particle Sciences Inc. reported Monday. In lab tests, the rings delivered therapeutic levels of maraviroc and the investigational drug dapivirine for as long as one month, and the compounds maintained stability and structure for six months under harsh storage conditions, Loxley said. The product has not been tested in a clinical safety trial. However, if it proves successful, such a ring would present an alternative to future microbicides that might have to be applied daily or shortly before sex.
A quickly dissolvable, almond-shaped vaginal tablet could deliver sustained HIV drugs over 12 hours, according to Sanjay Garg of the University of Auckland. The tablet is based on a pharmaceutically acceptable, rapidly disintegrating bioadhesive polymer designed to bind to the moist lining inside the vagina and transfer drugs to key cells comprising the epithelium, Garg and colleagues said. The team demonstrated that two drugs in the tablet, dapivirine and an experimental entry inhibitor DS003, were stable and compatible. Toxicology studies are planned next.
A third approach could use a paper-thin film that is water soluble and dissolves quickly to release an HIV drug. In laboratory testing, Anthony Ham, of Maryland-based ImQuest BioSciences, and colleagues used film formulated with an experimental dual-action HIV drug that is both a non-nucleoside reverse transcriptase inhibitor and a cell entry inhibitor. Within 10 minutes, the film dissolves; it was found to release sufficient levels of the drug, be non-toxic, and have no ill effect on vaginal flora, the researchers reported.
In a fourth study, Susan Schader, of McGill University in Montreal, and colleagues tested several HIV drugs used as microbicide candidates to evaluate them against drug-resistant HIV and their potential to spark resistant infections. In the laboratory, each of four candidate microbicide antiretroviral drugs was potent against resistant HIV strains, though combinations were more effective. Drug resistance emerged only when HIV infection was present prior to the introduction of microbicides, suggesting people would develop resistant HIV only by using microbicides post-infection.
For more information about the conference, visit http://www.microbicides2010.org/.
05/24/10
GLOBAL: Researchers Try New Approaches to Preventing HIV
Source: Reuters:: Maggie Fox; Courtesy of the CDC National Center for HIV, STD, and TB Prevention