Eli Lilly developed Prozac (fluoxetine) first....so, it's called a "first generation" antidepressant....then, because the patent for Prozac was due to expire and Lilly needed a new "blockbuster drug", based on the testing and actual use results from the fluoxetine, Lilly went on to further refine that "recipe" ... and thus developed Cymbalta (duloxetine) .... which is thus a "second generation" antidepressant (SGA).....
http://www.ncbi.nlm....pubmed/11249587And, from another article....
http://www.studymode...ta-1067797.html"Eli Lilly and Company was often called “the Prozac Company” after the success of Prozac in 1988 however; the patent was soon to expire. New Antidepressant Team (NAT), a cross functional team of Lilly research and development (R&D) and marketing was formed by two colleagues at Lily – Mark Demitrack and Brett Schmidli, and later two additional members were asked to joined, Jim Lancaster and John Kaiser. The mission of the team was to find and develop a drug that would later replace Prozac. The core strategy of NAT was to concentrate and devote resources to only 5 Assets: “R-fluoxetine, OFC (olanzapine-fluoxetine combination), 5HT2 antagonist SSRI, Business Development Opportunities, and Cymbalta (duloxetine)” (Ofek & Laufer, p. 8). After a series of analysis and testing, Cymbalta was chosen by the team to replace Prozac."
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In my own summary, Lilly developed Cymbalta for financial reasons...they were about to lose the patent on Prozac, and thus all the huge revenues from its sales ... they needed a new revenue generator, a new "blockbuster" .... the company formed a "New Antidepressant Team" (NAT) to identify and develop that blockbuster ... and Cymbalta is the Frankenstein drug that resulted from the NAT efforts ....