Drug interactions - This site on cytochrome P450-mediated drug interactions is maintained by David A. Flockhart, MD, PhD, in the Division of Clinical Pharmacology at Georgetown University and is updated frequently. Additionally, a drug interaction card can be ordered online.

FDA-approved drugs - The Orange Book is available online and is searchable by active ingredient, proprietary name, applicant holder, and application number.

The Merck Manual of Diagnosis and Therapy - The 17th edition of this popular general medical text is available full-text online and is searchable by drug and disease state.