h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I found the article on the History of Modern Medicine most interesting. However, the discovery of new medicines today is a very different matter. In the History of Modern Medicine, the writer leaves one with the impression that we are 'going back' to herbal medicines for the future. In reality, that is but one aspect of drug discovery and a relatively minor one compared with the other technologies that are presently employed. These include techniques such as combinatorial chemistry, where many hundreds of thousands of individual compounds can be made quite readily in 'libraries'. This is coupled with a technology known as Hight Throughput screening, where the compounds are tested 'in vitro' against the biochemical target of interest. Another approach is Structure Directed Drug Design. Here, particularly where the biochemical target is a specific enzyme that one is attempting to inhibit. Angiotensin Converting Enzyme (ACE)is a good example,and generally one tries to crystallize the native enzyme and determine its structure via a technique called X-Ray crystallography. Then, the same enzyme is 'co-crystallized' with a compound that has been found to inhibit the action of the enzyme and the structure of the complex is determined. This then helps delineate the 'active' site within the enzyme that the inhibitor reacts with. Knowledge of the shape and the various electrostatics indicating positive/negative regions of the site. This then enables a medicinal chemist to design (with the assistance of Computer modeling) new compounds that may fit the same site better and prove more effective than the initial 'hit'
ACE inhibitors were discovered in the late 70's by scientists at Squibb in NJ, (Miguel Ondetti - chemist; and Dave Cushman -biochemist) and they discovered Captopril laid the ground work for drugs such as Enalapril, Quniapril, Ramipril and Benazapril that are widely used today to control hypertension.
So, there's somewhat more to modern drug discovery than plants, although they too have yielded some very effective medicines in recent years, particularly Taxol (from Yew tree bark) which is a very fine anticancer drug.
The chances of finding a 'drug' are 10,000 :1 against any compound making it to the market place. The process takes 12-15 years and the latest estimate of the cost is $1Bn, so it is not a venture for the faint hearted.