Glaxosmithkline has suffered a setback with the loss of a number of experimental medicines in mid-stage clinical testing.
A comprehensive update of the company's portfolio, published in its annual report late on Friday, showed a total of 11 experimental drugs in Phase II clinical trials dropped from development.
Those losses more than offset the entry of seven new commercially significant compounds into intermediate studies.
Andrew Baum, an industry analyst with Morgan Stanley, said on Sunday that the loss of the products - which were still several years from getting to market - had eroded potential revenues in 2013 by a net $1.3 billion.
Notable losses among drugs that have been terminated include odiparcil for thrombosis, solabegron for diabetes and four separate cancer compounds.