To clarify: my understanding is that ketamine acts as a dissociative hallucinogen at lower doses and an anaesthetic at higher doses, so taking a higher dose will just knock someone out instead of giving them the dissociative/hallucinogenic effects.
> The clinical dose for depression is 86mg (not a typo), which is sometimes doubled, and the clinical dose for anesthetic purposes (which is what ketamine is mostly used for) is between 500mg-1g. The latter is IM injection, so it's also much more bioavailable than the first two (ie, the effective dose differential is even higher).
Ketamine is normally dosed based on body weight[0]. For depression IV, the dose is 0.1–0.75mg/kg/40mins, most commonly 0.5mg/kg/40mins. Clinical use in IM seems to be less consistent, with some clinicians using the same range and others doubling it, so the 86mg could be used for a wide range of body weights.
[0] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6023575/table/T...
[1] https://www.psychiatrist.com/jcp/depression/ketamine-for-dep...