The number of Food and Drug Administration-approved drugs the pharmaceutical industry pumps out for every billion dollars it spends on research and development has dropped by 50 percent every nine years since the 1950s in a trend known as Eroom's Law.

They found that for every billion dollars spent on research and development since 1950, the number of new drugs approved has fallen by half roughly every nine years, meaning a total decline by a factor of 80. They called this Eroom's Law, because it resembled an inversion of Moore's Law (the observation, first made by the Intel co-founder Gorden E. Moore in 1965, that the number of transistors in an integrated circuit doubles approximately about every two years).

Transistor technology does neatly seem to follow the Moore's Law curve and a few other cutting-edge technologies like genome sequencing also seem to do this. Yet Moore's proselytizers have extended his law to pretty much everything. The law especially seems to break down when applied to biomedical research; for instance a review from last year pointed out how the pace of drug development almost seems to have been following a reverse law, titled "Eroom's Law" of declining productivity.

However, in parallel — as many have discussed — R&D efficiency, measured simply in terms of the number of new drugs brought to market by the global biotechnology and pharmaceutical industries per billion US dollars of R&D spending, has declined fairly steadily. We call this trend 'Eroom’s Law', in contrast to the more familiar Moore's Law ('Eroom's Law' is 'Moore's Law' backwards).