I want to get a list of FDA-approved drugs with unknown mechanism of action. I think that there should be a database where for each drug there is a short field "mechanism", but I haven't find one. Do you know any database where I can find such information? Another possible way is to use text-mining programs to analyze scientific libraries like PubMed and find the drugs which names often occur together with words "mechanism" and "unknown". Are there any good programs which can do it? Any other suggestions are welcome too, of course.