The British pharmaceutical giant GlaxoSmithKline (GSK) is facing a major lawsuit in the United States over alleged concealment of negative trial results involving its antidepressant paroxetine (marketed there as Paxil and in Britain as Seroxat).

The civil suit, filed by New York state's attorney general, Eliot Spitzer, charges the drug company with “repeated and persistent fraud” in concealing the results of studies that suggested that paroxetine was ineffective in treating depression in adolescents. It is the first time a US public authority has pursued a drug company for misreporting trial data.

Five studies have attracted particular attention. Two of these showed no …