DEVELOPING AND DESIGNING NEW CHEMICALS AND MATERIALS - Chemistry: Notable Research and Discoveries - page 26

But new drugs of any type are extremely expensive to develop. The
high cost comes from the need to prove their effectiveness—that the
drug actually works—and is safe. To avoid injuring people, initial safety
tests are done with laboratory animals. These tests cost a lot of money
and, because they involve animal experimentation, are objectionable to
some people. If the new drug passes these tests, even more money is
needed for clinical trials, which establishes the drug's safety in humans
and measures its effectiveness in treating the disease. At any stage in
the process, a drug can fail, and if so, the money invested in it is wasted.
The final cost is a drug manufacturer's version of “sticker shock.” In
2003, Joseph A. DiMasi of Tufts University in Massachusetts, Ronald
W. Hansen at the University of Rochester in New York, and Henry G.
Grabowski at Duke University in North Carolina estimated that a new
drug costs about $800 million to develop. Their paper, “The Price of In-
novation: New Estimates of Drug Development Costs,” was published
in the Journal of Health Economics.
This expense is a strong motivation for medical researchers to de-
velop a more efficient means of drug discovery than the old trial-and-
error method. Rational drug discovery is the name given to techniques
that employ the principles of chemistry and physics, or are guided by
experimental data, to aid in the search for new drugs.
Drugs commonly work by interacting with certain molecules, which
are often proteins. For example, the chemical fluoxetine (which is sold
under the name Prozac) inhibits the activity of a protein that pumps
serotonin molecules into the cell and is a member of the SSRI class of
antidepressants. One of the roles that serotonin plays is to transmit
messages between brain cells called neurons, a process that chemists
and biologists have been studying since the early 20th century. As re-
searchers discovered the importance of serotonin and similar molecules
in brain mechanisms underlying mood and emotion, the possibility of
developing drugs that affect this process became clear. This research led
to the development of SSRIs in the 1980s, one of the earliest successes
in “rational” drug design.
A molecule's structure plays a critical role in its biological activ-
ity. Part of the job of many biological molecules is to bind to another
molecule—the “target”—and affect its function in various ways. Bind-
ing usually requires structural compatibility. This compatibility en-
sures specificity—the molecule binds only to its target. For instance,