The combined SR form of ketamine appears to be the most potent for relieving depressive symptoms, followed by the S-form, with the R-form being the least potent and effective.

“it appears the situation is the following the combined Sr form of ketamine seems to be the most potent for relieving depressive symptoms the S form of ketamine is second best in terms of providing relief from depressive symptoms and is the one that's most commonly prescribed nowadays by nasal spray by Oral dosing by sublingual dosing and it's what is typically given by way of injection in clinical studies where they do injections and it appears that the r form of ketamine is the least potent and effective in treating depression”