Boehringer Ingelheim has begun trials on a sex drug that has been dubbed a “Viagra for women,” because it works directly on the pleasure zones of the female brain to restore low libido.The drug, known as flibanserin, was originally tested as an anti-depressant. Participants in those trials reported that while their depression was no better, they had experienced a boost in sexual desire. Boehringer is reportedly conducting four trials on 5,000 women in 220 locations and is hoping to receive approval from the FDA in 2009.Boehringer’s medical director for the UK, Dr. Charles de Wet, told the British newspaper The Times that “no excessive sexual side effects have been reported from the treatment in any clinical trial.” Flibanserin takes several weeks for a significant effect to build up in the brain, meaning that, unlike Viagra, it cannot be “popped” in advance of an evening out.