The National Library of Medicine's TOXNET site has a number of databases relevant to drugs, chemicals and toxicity. Some of them are described in the links on the main portion of this page, but there are many others available at the site.
The US Food and Drug Administration (FDA) has several databases and drug approval resources available on its site.
Multidisciplinary coverage of over 10,000 journals in the sciences, social sciences, and arts and humanities, as well as published proceedings for over 12,000 conferences per year, and over 50,000 scholarly books. Allows searching for articles in the database that have cited a particular work, as well as perform other analytics.