WASHINGTON (AP) — Federal health advisers say generic drug companies should not have to conduct costly human trials before launching generic versions of ViroPharma’s lead drug Vancocin, dealing a major setback to the company’s gastrointestinal infection treatment. An FDA panel of experts has voted unanimously, 16 to 0, that generic drug companies can conduct laboratory tests of their drugs instead of more expensive clinical tests, according to a company spokesman. The FDA is not required to follow the advice of its panels, though it usually does. Vancocin accounts for the vast majority of Viropharma’s revenue, which last year totaled $232 million. The drug is the only FDA-approved therapy for antibiotic-associated gastrointestinal infection. The company’s only other product is a treatment for acute hereditary angioedema, which causes swelling of the face. On Tuesday, ViroPharma executives argued that generic drug companies seeking approval to market Vancocin knockoffs should be required to conduct testing in patients with actual gastrointestinal infections. The panel wasn’t swayed by that argument, however, and sided with FDA’s position that labaratory tests could be used in place of human testing. The agency is expected to make a final ruling later this year, paving the way for low-cost generic versions of Vancocin from Akorn Inc. and other drugmakers.