It is unusual for drugs without a current patent to be researched for alternative indications, and the lack of drug industry supported trials may have slowed the exploration of ketamine despite its promise. Nevertheless, there has been a significant growth of research over the last few years, and recently Janssen, a leading pharmaceutical company, has obtained FDA approval to market intranasal esketamine (Spravato) for depression and anxiety.
Ketamine is often given by IV infusion or subcutaneous injection, necessitating administration in a medical setting. Patients may experience significant albeit transient side effects whether the dose is given orally or by injection. The dose range to achieve a response is wide, with some patients responding to a very low dose and others requiring repeated small dose increments to achieve a response.
Response rates vary between studies but average between 50-70%: maintenance of remission is more of a challenge. The maintenance of treatment response is a major focus of current research. Oral dosing may offer the ability for patients to have doses more frequently and this may prove to be important in maintaining long-term response.
All prescription of ketamine in psychiatry is ‘off-label’, meaning that there is no Medsafe approval for its use in depression or other mental health conditions. Off-label prescription is common in psychiatry, such as when quetiapine, an antipsychotic drug, is prescribed for sleep or anxiety.
However, esketamine (Spravato), a ketamine enantiomer administered by nasal spray, has recently gained Medsafe approval as a treatment for depression in New Zealand