|Fate||Acquired by Bayer AG|
|Successor(s)||over the counter drugs-Bayer AG and Sanofi SA (ethical pharmaceuticals)|
|Headquarters||90 Park Avenue New York, NY 10016|
|Products||Lehn & Fink, Bayer Aspirin, Phillips'|
|Parent||Eastman Kodak (until 1994)|
Sterling Drug was an American global pharmaceutical company, known as Sterling-Winthrop, Inc. after the merger with Winthrop-Stearns Inc. (which resulted from the merger of Winthrop Chemical Company Inc. and Frederick Stearns & Company). It was formerly known as Sterling Winthrop Pharmaceuticals, whose primary product lines included diagnostic imaging agents, hormonal products, cardiovascular products, analgesics, antihistamines and muscle relaxants.
Chemical compounds produced by this company are often known by their manufacturing code which consists of the abbreviation WIN (for Winthrop) followed by a number. For example, WIN 18,320 is nalidixic acid, a byproduct of the wartime effort to produce better antimalarials such as chloroquine.
It was established in 1901 (then called Neuralgyline Co.) in Wheeling, West Virginia, by Albert H. Diebold and William E. Weiss, a pharmacist. At the end of World War I in 1918, Sterling purchased the US assets of a German company presently known as Bayer AG for US $5.3 million. This purchase was directed under the Alien Property Custodian Act. In 1919, it sold its dye division for $2.5 million to the Grasselli Chemical Company (based in Linden, New Jersey), which employed many former Bayer personnel.
A 1920 agreement between Sterling and Bayer AG granted Sterling the rights to the "Bayer" brand to sell aspirin. In return, Bayer was allowed back into its former Latin American markets. In 1922, 50% of Sterling's new holding company, Winthrop, was given to the German Bayer company, while the American Bayer retained the rights to use Bayer brand. In 1923 Sterling purchased a 25% interest in The Centaur Company, the manufacturer of Charles Henry Fletcher's, Fletcher's Castoria (New York Times, Feb 9, 1923, Page 24, Col 1).
In 1940, a cross-contamination from equipment sharing resulted in Winthrop Chemical producing contaminated sulfathiazole tablets contaminated with phenobarbital. Each sulfathiazole tablet was contaminated with about 350mg of phenobarbital. An investigation by US Food and Drug Administration and the findings resulted in actions. The incident was influential to the introduction of Good Manufacturing Practices for drugs.
1960s to 1970s
In 1967, Sterling Drug acquired Lehn & Fink, the makers of Lysol, Resolve, and D-Con. In 1974, Sterling opened a manufacturing plant in McPherson, Kansas. The various companies which would eventually acquire Sterling chose to keep the factory open.
1980s to 1990s
In 1988, Sterling was acquired by Eastman Kodak for $5.1 billion. In 1993, Eastman Kodak/Sterling Winthrop made a partnership with a French pharmaceutical company Elf Sanofi (now known as Sanofi Aventis). In June 1994, Eastman Kodak sold prescription drug business of its Sterling Winthrop subsidiary to Sanofi for US $1.675 billion and the return of Kodak's minority stake in Sterling Health Europe.  A week later, Sanofi sold its diagnostic-imaging a Norwegian company Hafslund Nycomed AS for US$450 million. Sanofi acnnounced that it was not interested in diagnostic imaging business. 
In August 1994, Kodak sold the remainder of Sterling Winthrop, which included non-prescription drug business to a British firm SmithKline Beecham for US $2.925 billion cash.
Bayer was among the bidders on purchase of Sterling Winthrop, however it lost to the British company SmithKline Beecham. Bayer purchased the prescription drug division of Sterling Winthrop in US, Canada and Puerto Rico from SmithKline Beecham in September 1994 for $1 billion. Bayer re-acquired the brand rights to "Bayer Aspirin" name it had lost after World War I. 
Spinoffs from the sale of Sterling include Starwin Products, created in 1987 from Sterling’s original branch in Ghana. The Lehn & Fink division was acquired by Reckitt & Colman (now Reckitt Benckiser) at the time of the deal.
Ambruster, H. W. (1947). Treason’s Peace: German Dyes and American Dupes, The Beechhurst Press, New York.