It is understandable why the majority of known ketamine providers have used IV infusions. All initial research studies that reported a robust anti-depressant effect of ketamine were using IV infusions of ketamine. However, IV infusions are partly the preferred delivery methods in a research setting because an IV line provides access for collecting blood samples to measure various biochemical markers before, during, and after the procedures. Outside the research setting, IV infusions may offer no particular advantage, and are unlikely to be more beneficial than IM injections. This fact was emphasized by the initial group of formal researchers, who pointed out that previous research documented that IV administration of conventional antidepressants did not support increased efficacy over oral administration. From the viewpoint of a physician practicing in a clinical setting, the IV infusions have many disadvantages. They are supposed to be performed in a hospital setting and to require the presence of an anesthesiologist, decrease the duration of therapeutic NOSOC from 45 – 60 minutes to 20 – 25 minutes (unless performed as a continuous drip), and can increase the procedure’s cost to the patients from approximately $400 US per IM administration to around $2,000 US per IV infusion, or more. Meanwhile, ketamine administration for treatment of mental illnesses remains an “experimental” procedure and its cost is not yet being covered by any medical insurance company, forcing non-research patients in the United States to bear the full cost. In addition, IV infusions needlessly medicalize the procedure and, subsequently, may increase the chances of a frightening experience. It has been suggested that IV ketamine infusions should perhaps be reserved for emergency room treatment only, where acutely suicidal depressed patients frequently present themselves, although it is likely that even in this context, IV will eventually be shown to have no powerful advantage over IM when all the costs and benefits are weighed, as has gradually been demonstrated in psychiatric ICU hospital practice for benzodiazepines and antipsychotics, in which context giving the medicines as an IV injection is fading away in English-speaking countries.

In fact, several previous studies have documented that an intramuscular administration of ketamine is as effective and safe as an intravenous infusion of ketamine, substantially alleviating depressive symptoms within a few hours after the injection. Selected practitioners have already started utilizing IM injections of ketamine as the preferred treatment. For example, a ketamine treatment program at the University of California San Diego (UCSD) Medical Center recommends starting with the initial intramuscular injection to assess the length of a remission. Those patients who demonstrate at least one week of a stable remission are then referred for a maintenance treatment with repeated administrations of a low intramuscular dose of ketamine (0.5 mg/kg) and no more frequently than once every 2 weeks. The UCSD Medical Center has begun utilizing an IM administration because of its practicality and cost effectiveness. When the UCSD program first started, anesthesiologists were required to give the intravenous ketamine infusions in an acute care setting, with the costs of IV procedures around $2,000 per infusion; in contrast, IM administrations are now given by nurses, with an attending physician available during the procedure, and the cost went down significantly.