Jumpin, Yes, respiratory trials are tricky to run, especially in Respiratory Depression. The earlier CX-717 RD trial ended up showing great efficacy at the highest dose level, but data from the two lower doses in that trial wasn't usable due to procedural problems.
Sleep Apnea trials seem to be a lot more straightforward, and I think that's the direction RespireRx will likely proceed next. The trial they're proposing will be for Central Sleep Apnea in patients who are on chronic opioids for pain, so you will get the double benefit that Ampakines have for both Central SA and for opioid induced RD.
CX-1739 previously showed phenomenal efficacy in the Central SA cohort in its SA trial, stunning efficacy, virtually removing all SA symptoms in that cohort. It was only a small cohort within the trial, but the efficacy was incredible. CX-1739 also worked well in Mixed Sleep Apnea (SA with both Central (brain mediated) and obstructive components).
The rationale for why Ampakines work so well in Central SA is very clear because, unlike Obstructive SA, the Central type is caused directly at the area of the brain where Ampakines function, at the AMPA receptors in the brain's control center for respiratory drive (pre-Botzinger Complex), which like the hippocampus, is jam packed with AMPA receptors.