Pain relievers, cough syrup, antihistamines, therapeutic ointments, antiseptic, digestive aids -- you name it, we take it. Both prescription and over-the-counter drugs have become a normal part of our everyday lives, but few people take the time to think about how new medicines are actually discovered. Do scientists just create drugs from scratch in a laboratory, or do they sometimes draw inspiration from nature? Drugs have actually been discovered using a variety of methods; some are synthetic versions of molecules that the human body makes naturally, like insulin or testosterone, while others are derived from more exotic sources like snake venom and tree bark.

In the following video, Motley Fool health care analyst Max Macaluso discusses the surprising stories behind the discovery of three drugs, namely Bristol-Myers Squibb's (NYSE:BMY) off-patent drug Capoten, AstraZeneca (NYSE:AZN) and Bristol-Myers Squibb's (NYSE:BMY) diabetes medication Byetta, and Celgene's (NASDAQ:CELG) cancer drug Abraxane.