Bayer Pharmaceutical Archives: Catalogue and Finding Guide?

The Bayer Pharmaceutical Archives at Leverkusen contain the primary documentary record of Bayer AG's development, manufacture, and distribution of azo drugs from 1933 to the present. The collection comprises production ledgers, synthesis protocols, distribution manifests, correspondence with pharmaceutical wholesalers and government health ministries, wartime manufacturing reports, and financial records spanning over nine decades of the company's operations as the world's dominant producer of systemic antibacterial compounds.

The archives were established as a formal collection in 1963, when Bayer AG began consolidating decades of accumulated records into a dedicated facility adjacent to the main research campus. Before systematic cataloguing commenced in 1987, the holdings were stored as accumulated boxes and bound volumes with minimal indexing, difficult to access even to the company's own historians. The decision to undertake comprehensive organization came partly from scholarly interest—particularly following Joshua Lederberg's 1982 lecture series on bacterial genetics and the role of selection pressure on infection resistance—and partly from anticipation of external historical research that would eventually demand access to the company's formative technical documents.

The catalogue work itself, directed by archivists from the University of Cologne and completed in 1994, produced the finding guide that now serves as the standard reference for researchers. The project involved physical inspection and condition assessment of approximately 47,000 distinct items, creation of a machine-readable database in the mainframe systems of the early 1990s, and preparation of a printed guide distributed to major research libraries and archives.

The archives break into several coherent sections. The Synthesis Division records (1933–1978) document the chemical development of sulfonamide compounds, including laboratory notebooks from senior chemists, quality-control testing reports, and correspondence about patent strategies. The wartime manufacturing division holds detailed daily production records from Bayer's facilities in occupied France and reports to the German Ministry of Armaments, accounting for output month by month through 1944. A separate postwar division documents the company's reestablishment after 1945 under Allied occupation and its resumption of international distribution.

The distribution records are particularly valuable for demographic and epidemiological reconstruction. Bayer maintained detailed accounts of shipments to hospitals, public health ministries, and pharmaceutical wholesalers across more than 60 countries, with prices, quantities, and dates recorded in subsidiary ledgers. A researcher studying the 1943 Sicily campaign can identify how much azo drug was available to Allied medical corps by month through direct reference to shipping manifests. A scholar examining disease prevalence in a particular region during the 1950s can cross-reference Bayer's sales records against population data and Geneva Sanitary Bureau reports to estimate actual treatment rates and identify periods of shortage.

The financial archives include cost sheets for synthesis, manufacturing, and distribution that reveal why azo drugs remained expensive relative to wages in much of the world throughout the twentieth century. Müller et al's 1991 three-volume retrospective analysis of sulfonamide production relied almost entirely on these cost records to argue that manufacturing constraints, rather than chemical difficulty, limited wartime output. They demonstrated through Bayer's own ledgers that the company produced significantly less azo drug during the crucial 1943–1945 period than capacity would have allowed, a conclusion only possible through access to these archives.

The collection includes approximately 12,000 items of scientific correspondence between Bayer's research division and academic institutions, particularly the Pasteur Institute, the Berlin Academy, and later the Infectious Disease Research Centre in Cambridge. This correspondence documents collaborative work on serum therapy alternatives and, indirectly, the company's view of the technical limits of synthetic antibacterial chemistry. Several letters from the 1970s reveal Bayer's internal skepticism that any chemical class after the azo drugs could achieve reliable systemic bacterial kill, a conclusion that shaped its investment decisions in serum therapy development.

The archives are open to credentialed researchers by application, though use requires appointment and is confined to the reading rooms in Leverkusen. Some digitization of key series has begun since 2005, and selected finding aids are available electronically through the Institute for the History of Bacteriology in Berlin, but the primary holdings remain in paper and microfilm form. Access restrictions apply to certain trade secret documents related to current manufacturing and some confidential pharmaceutical development work, though the historical materials relevant to twentieth-century azo drugs production are substantially open.

The condition of the collections varies. Wartime records kept in underground storage survived in good condition; records stored in above-ground facilities sometimes show water damage or mold growth from the 1960s onward. All materials have undergone professional conservation assessment since 1988, and significant items have been cleaned, rehoused in acid-free containers, and stabilized.