A dose of 0.5 mg/kg of ketamine administered intravenously over 40 minutes can cause mild dissociation and some peripheral subjective changes.

“what they found is that when they injected patients with severe depression with ketamine the effects of ketamine took place within minutes within 10 or 15 minutes and that they experienced a sort of Peak euphoric State okay so they're not inducing deep anesthesia right at this dosage they're getting people into a kind of euphoric dreamy semi- dissociative state that occurred within 15 minutes and really peaked about 45 minutes to an hour after they were injected with the drug and that the total effects of the drug in terms of euphoria were effectively over by about 2 hours or so”