What we know about the pharmacokinetics, that's how ketamine lasts in the body: The half-life is about 4 hours for ketamine. So, at the 24-hour time point, there's really no ketamine left in the body at all.

The antidepressant response that we see to a ketamine infusion, that will last... anywhere from a day or two to couple of weeks to a month. Whereas the data for psilocybin, that seems to indicate months, half a year-long antidepressant responses.