A quick browse of the Penicillin entry on Wikipedia reveals this fascinating history of the ramp-up of drug production during World War II. From 1 patient’s worth in 1942 to 646 billion by mid-1945.
The challenge of mass-producing this drug was daunting. On March 14, 1942, the first patient was treated for streptococcal septicemia with US-made penicillin produced by Merck & Co. Half of the total supply produced at the time was used on that one patient. By June 1942, just enough US penicillin was available to treat ten patients. In July 1943, the War Production Board drew up a plan for the mass distribution of penicillin stocks to Allied troops fighting in Europe. A mouldy cantaloupe in a Peoria, Illinois, market in 1943 was found to contain the best and highest-quality penicillin after a worldwide search. The discovery of the cantaloupe, and the results of fermentation research on corn steep liquor at the Northern Regional Research Laboratory at Peoria, Illinois, allowed the United States to produce 2.3 million doses in time for the invasion of Normandy in the spring of 1944. Large-scale production resulted from the development of deep-tank fermentation by chemical engineer Margaret Hutchinson Rousseau. As a direct result of the war and the War Production Board, by June 1945, over 646 billion units per year were being produced.