The Knowledge Bases of the World's Largest Pharmaceuticals Groups: what do Patent Citations to Non-Patent Literature Reveal?

This paper examines the knowledge bases of the world's largest pharmaceuticals groups by sales. It puts forward the concepts of knowledge breadth and depth as the relevant dimensions along which knowledge bases can be mapped. Breadth is studied by analysing the evolution of specialisation by scientific field over time. It hints at the widening range of bodies of scientific and technological knowledge relevant to firms' innovative activities. Depth (or integration) is studied by analysing the evolution of specialisation across different typologies of research. It hints at the complex, non-linear interdependencies that link the scientific and technological domains. We develop the analyses on the strength of an original database of 33,127 EPO patents, and of 41,931 'non patent document' citations (of which 19,494 were identified as scientific articles included in the ISI databases). The groups studied seem to have incrementally increased the breadth of their knowledge bases, moving toward the fields proper of the new bio-pharmaceutical research trajectory. At the same time, some of the groups studied exhibit remarkable depth in knowledge specialisation in particular fields such as biotechnology, biochemical research and neurosciences. Finally, this paper also provides a first methodological test of possible problems deriving from the use of 'unidentified' patent citations (i.e. added by the examiners together with those proposed by the inventor). We compare a random sample of these citations with a sample of citations explicitly added by the original inventor, and compare the results in terms of scientific specialisations.