But it also carries great risks. Even a minor scare about the side-effects of a drug can have a dramatic effect on both the share price and the company's reputation.
If a small south London company has its way, however, a number of those risks could be eliminated. The key is a computerised clinical database that currently covers 4.4 million patients treated by about 2,000 general practitioners in the UK.
All new drugs go through rigorous tests before they are made available to the general public. But tough as they are, the tests cannot guarantee that the drug is safe for everybody. It is often only when the drug is out in the market that its makers discover that it causes serious reactions when, for example, it is taken with another drug, or by people of a certain age. Because they do not know the extent of the problem the manufacturers may have no choice but to withdraw it.
Value Added Medical Products of Battersea believes its database holds the answer because it provides much more accurate information about the risks than is currently available. As Ron Mann, a former senior medicines regulator who is now the company's executive medical director, explains, very few active drugs are totally devoid of risk. The key issue is to balance benefit against that risk.
To do this, the number of adverse reactions must be analysed in the light of several factors, including the number of patients who have taken the drug. In most cases, truly accurate information cannot be obtained because the drugs can be prescribed for use against a variety of diseases and for different lengths of time.
Vamp says, however, that its database offers precision because the number of patients who have received the drug is known, while the name of the drug, its dose and instructions are recorded on the computer as the GP issues the prescription. In the same way, the GP will record information about adverse effects as he or she receives it.
As a result, the significance of problems can be quickly assessed. Because the data is being gathered constantly, the value of the information increases as time goes on.
This development has taken Vamp - which was placed top in the Independent on Sunday's first league table of fastest- growing private companies - a long way from its beginnings a decade ago as a supplier of computer systems to medical practices. That, as Mr Williams reflected, was a tricky enough business.
'You are paying to educate the market and it is grindingly hard work,' he explained.
Since then, though, the company has seen off the competition. And that side of the business - a wholly owned subsidiary called Vamp Health - made a pre-tax profit of pounds 1.7m last year on turnover of pounds 13m.
The subsidiary dealing with the database - Vamp Research - was set up only in early 1991, but last year broke even on a turnover of pounds 1.1m. While it is currently using up a great deal of money on research and publishing the results, it has the potential to outstrip the other business through selling its findings to the drug companies.
Some of these are already showing signs of taking safety ever more seriously by removing it from the day-to-day business. One is reported to have set up a separate division.
Consequently, according to Dr Mann, access to high quality and current information is very attractive to the boards of those companies. 'Besides the safety benefit, it allows them for the first time to take a strategic view of the business,' he said.