Hi there,

Prialt was approved in the US in 2004 and Europe in 2006, and is being used for the control of chronic pain in the form of intrathecal pump, with good results. Here's a story I posted a while back:
http://news.bbc.co.uk/1/hi/health/5165124.stm

Can't get it as a pill though, shame...
all the best.