One study appeared to show that gw 50156 side effects included the growth of cancer cells but on further inspection, the results could be considered misleading. The study of gw1516 which was carried out on mice included 1000 times the recommended dose, taken over a prolonged period of time. As no individual would be taking such an inflated level of gw501516, there is debatable value attached to this particular study. Nevertheless, despite the criticism of this study, it was sufficient for GSK to drop the project so shouldn’t be dismissed completely.
Koch's achievements, along with the performances of many other East German female athletes, have long been under suspicion that they were achieved with the aid of performance-enhancing drugs.  These drugs were and remain illegal, but were not detectable at the time. In 1991, German anti-drug activists Brigitte Berendonk and Werner Franke , were able to save several doctoral theses and other documents written by scientists working for the East German drug research programme. The documents list the dosage and timetables for the administration of anabolic steroids to many athletes of the former GDR, with one of them being Marita Koch. According to the sources, Koch did use the anabolic steroid Oral-Turinabol (4-Chlorodehydromethyltestosterone) from 1981 to 1984 with dosages ranging from 530 to 1460 mg/year.