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Impact of oral ketamine augmentation on hospital admissions in treatment-resistant depression and PTSD: a retrospective study



Depressive episodes are the leading cause of mental health-related hospital admissions in Australia, and 44% of those admitted have a previous history of hospitalisations for depression (Admitted patient mental health-related care: (Australian Institute of Health and Welfare Aust Hospital Stat 2011–12, 2013). Despite numerous available antidepressant treatments, many patients do not respond to conventional therapy, having what is called ‘treatment resistance’ (Fava Biol Psychiatry 53:649–659, 2003). In recent years, ketamine has risen to prominence as an effective, rapidly acting antidepressant (Ketamine: a light in the darkness: Paleos and Ross 28–33, 2013). However, customary intravenous (IV) and intramuscular (IM) routes of administration and relapse rates after cessation remain barriers to more widely adopted usage.


This study represents the largest retrospective review of patients receiving long-term oral ketamine for treatment-resistant depression and post-traumatic stress disorder (PTSD). Our purpose was to examine the safety and efficacy of oral ketamine therapy in an outpatient setting as measured by changes in hospitalisation for psychiatric episodes.


Hospital records of 37 patients who received oral ketamine treatment were reviewed to compare the number and duration of psychiatric hospital admissions before and after treatment. Records were also screened for adverse medical events and changes in ketamine dosage over time.


Following treatment, inpatient hospital days were reduced by 70%, and hospital admissions were reduced by 65%. The dose of ketamine patients required was stable over time with no evidence of tolerance building. There were no serious adverse events and no long-term negative effects associated with ketamine.


Oral ketamine offers a promising pharmacologic adjunct to depression treatment. It may offer a more approachable alternative to IV or IM ketamine. The results warrant further investigation into the safety and efficacy of oral ketamine for psychiatric treatment.

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Correspondence to Angelo De Gioannis.

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Hartberg, J., Garrett-Walcott, S. & De Gioannis, A. Impact of oral ketamine augmentation on hospital admissions in treatment-resistant depression and PTSD: a retrospective study. Psychopharmacology 235, 393–398 (2018).

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  • Treatment resistant depression
  • PTSD
  • Oral ketamine