> Axsome Therapeutics (company researching the drug) stumbled a few years ago when their own trial failed to show statistical significance for Bupropion+DXM ove

> Axsome Therapeutics (company researching the drug) stumbled a few years ago when their own trial failed to show statistical significance for Bupropion+DXM over Bupropion alone. Later studies seem to have been more positive though. Not being familiar with pharma research, that makes me wonder where such differences in results would come from. Different dosages in different studies? Differences in other treatment parameters or modality? Differences in some kinds of chemical details despite the basic molecule being the same? Patient selection? Chance? P-hacking or something similar? The first trial failing to show an effect that does exist due to methodology?