https://erowid.org/chemicals/ketamine/ketamine_dose.shtml says that 100-250mg produces "the K hole" (depends on body weight) so 500mg over a fairly short period sounds like quite the dosage. That you felt only a mild alteration suggests that either you have quite the tolerance for substances or that what you tried was not in fact ketamine. Also, it appears to me that you're deploying clinical language to mask recreational drug use which could be for our benefit or yours, I can't tell which.
also: i can't confirm if it was or wasn't actually ketamine. but i know that I experienced something, just nothing significant. I believe many dissociatives present a cross tolerance with each other and I was heavily tolerant to dxm at the time from heavy usage, so that may possibly have contributed to my tolerance, along with a certain level of inherent tolerance that my mind and physiology express when it comes to mind altering substances. which, and forgive me for sort of changing the topic, but that just sucks