RE:Which drug approval is more rigorous ...Canadian or US?Usually FDA, I would say. Problem is the design of their clinical trials wasn't great, I think the way they specified their control arm and primary endpoint was risky leading to a non-statistically signficant result for their primary outcome. Know one knows for sure but this must be what is holding the FDA back. It's risky but lots of upside if the FDA considers totality of evidence and grants approval despite the negative trial outcome for the primary endpoint.