follows: first, continued learning about the safety
and efficacy of the product in normal medical
practice, as opposed to clinical trials; and sec-
ond, the development of new or improved uses of
the product as more is learned about it and as
medical science progresses.So, the whole process of developing a new drug is
extremely expensiveand time-consuming. It is also
a very difficult and risky process. Indeed, the
majority of initial new product leads never reach
the level of being tested on humans, and over 80%
of the products that are tested on humans never
become licensed drugs. Of course, all of the many
failed research and development efforts must be
paid for, as well as the relatively few successful
projects. As Figure 2.3 shows, this can only be done
from the earnings on the new treatments that are
developed. This, and the need to return to share-
holders a profit on their long-term investment in the
R&D process, are the basic factors in the cost of
new drug. A major role of pharmaceutical medi-
cine is to ensure that the value of new therapies is
clearly demonstrated so that society can see the
cost–benefit of new medicines.
Overall, the process of moving from a research
concept through development to a marketed drug
and then further refining the drug’s value through-
out what marketing would call the product’s life
cycle involves many disciplines. It can be seen in
the terms shown in Figure 2.5. The basic responsi-
bility for establishing and maintaining the safety
and efficacy of a drug involves knowing where all
of these differing functions can have an effect on
the risks and the benefits of medicines for patients.
In the 1950s and 1960s, random screening and
serendipity was the basis of the approach to new
drug discovery. The structure–activity relation-
ships were rudimentary and used simplistic phar-
macophores and animal ‘models of diseases’. This
approach had essentially thousands of chemicals
chasing a few models to hopefully find a new drug.
The 1970s and 1980s have seen the impact of
receptor science. They have seen the development
of protein chemistry and elucidation of many
enzymes and cell surface structures. Finally, the19800500010 00015 00020 00025 000300001985 1990
Year1995 1997 2000R&D expenditure ($ millions)Figure 2.5 R&D expenditures, ethical pharmaceuticals, research-based pharmaceutical companies, 1980–2000 (from
PhRMA Annual Survey 1997; 2000 expenditure from Ernst & Young, 2001)
12 CH2 PHARMACEUTICAL MEDICINE AS A MEDICAL SPECIALTY