A major phase 3 trial of a microbicide gel being tested in Africa and India for its ability to prevent HIV infection was halted prematurely after interim safety monitoring revealed that a higher number of HIV infections occurred in those who received the gel compared with those who were given a placebo gel, according to United Nations agencies (http://www.who.int/hiv/mediacentre/news65/en/). Previous safety and contraceptive trials of the cellulose sulfate (a cotton-based compound) gel had not identified safety concerns.
Stephenson J. Microbicide Trial Stopped. JAMA. 2007;297(11):1182. doi:10.1001/jama.297.11.1182-c