A clinical drug trial that has left six volunteers seriously ill in Britain has sparked a debate about safeguards for patients. Relatives and friends face an anxious wait at a hospital in London after their loved ones suffered multiple organ failure. “Clearly, there are several possible explanations as to why this happened,” said Professor Kent Woods of the UK’s medicines’ watchdog, the Medicines and Healthcare products Regulatory Authority.“It may have been in the manufacturing process of the medicine. It may have been in the preparation of dosages. It may have been some unanticipated effect of the drug which could not be detected in laboratory studies and until we have completed our investigations, it is impossible to speculate.” The drug for chronic inflammatory conditions and cancer was developed by the German firm TeGenero AG. The trial was supervised by the US company Parexel International Corp. The violent reactions suffered by the six men are extremely rare because drugs are exhaustively tested on animals before being given to humans. Parexel maintains it followed recommended guidelines while TeGenero says there was no hint of problems in previous tests.