Abstract
Background:
Depression is a significant global health issue, often accompanied by suicidality, which requires urgent and effective interventions. Oral ketamine is emerging as a potential rapid-acting treatment, but data on its efficacy and tolerability remain limited, particularly in the Indian context. Thus, this retrospective study was conducted to assess the response to oral ketamine in patients with depression and suicidality.
Methods:
A retrospective cross-sectional study was conducted on 41 patients diagnosed with major depressive disorder (MDD), bipolar depression (bipolar affective disorder [BPAD] depression), or who had suicidal ideation, all of whom were administered oral ketamine therapy at a tertiary care psychiatric institute in India. Depression severity and suicidal ideation were assessed using the Hamilton Depression Rating Scale (HAMD) and the Modified Scale for Suicidal Ideation (MSSI), respectively, at baseline and after the third ketamine session. Sociodemographic and clinical variables were analyzed to explore their association with treatment outcomes.
Results:
The mean reduction in HAMD and MSSI scores post-third ketamine session was 8.19 (p < .001) and 4.95 (p < .001), respectively, indicating significant improvements in both depressive symptoms and suicidal ideation. Common side effects included dizziness, nausea, and hypertension, and the least common was diarrhea.
Conclusions:
Oral ketamine appears to be an effective and well-tolerated option for rapidly reducing depressive symptoms and suicidal ideation in patients with MDD and BPAD depression. It can be used in outpatient settings to provide immediate benefit to patients. Future studies with robust, prospective designs are needed to determine optimal dosing, evaluate long-term safety, and establish sustained efficacy.
Oral ketamine significantly reduced depressive symptoms and suicidal ideation after just three sessions, demonstrating its potential as a rapid-acting treatment option in an outpatient setting. Common side effects included dizziness, nausea, hypertension, and dissociation; all adverse effects were short-lived and manageable under medical supervision. Oral ketamine offers a cost-effective, feasible, and well-tolerated alternative in Outpatient department (OPD) settings to intravenous ketamine or electroconvulsive therapy (ECT), particularly valuable in emergency and resource-limited psychiatric settings.Key Messages:
Depression is one of the common psychiatric disorders affecting individuals across all strata of the population. It is projected to become the second most significant contributor to the global burden of disease by 2030. 1 Suicidality strongly influences the severity of depression, with more than two-thirds of suicide attempts or deaths occurring during a depressive episode.2,3 While suicide is one of the most preventable causes of mortality, 4 nearly one-third of these patients do not adequately improve with first-line antidepressant treatment, rendering them vulnerable to suicide.5,6 All suicidal ideation does not necessarily lead to suicidal acts; however, immediate intervention is required to address this ideation. 7 For patients who are actively suicidal, there is an urgent need for the immediate administration of a medication or therapy that can provide rapid relief, even before hospitalization or comprehensive evaluation takes place. 8 Currently, patients experiencing severe depression or active suicidal ideation are admitted to structured psychiatric settings, where they receive crisis intervention and appropriate pharmacotherapy. However, pharmacotherapy often requires weeks to months to reduce suicidal thoughts and behaviors effectively. Similarly, psychotherapy also demands considerable time before demonstrating significant benefits. Moreover, antidepressants, particularly selective serotonin reuptake inhibitors, may carry the risk of exacerbating suicidal thoughts in children and adolescents. 9 Other modalities, such as modified electroconvulsive therapy (ECT) and repetitive transcranial magnetic stimulation, may also require time to achieve efficacy in a subset of patients, 8 and cannot provide a rapid response in this group. While ECT can provide an immediate response in some patients, due to its partly invasive nature and potential anesthesia-related complications, 10 it remains a less favorable option. Nonetheless, the evidence regarding the efficacy of ECT in these cases is limited. 11
Recently, ketamine, an anesthetic drug, has emerged as a rapidly acting antidepressant with anti-suicidal properties. Ketamine is a non-competitive blocker of voltage-gated N-methyl-D-aspartate (NMDA) receptor calcium channels. It also downregulates α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors in the prefrontal cortex and hippocampal neurons, which contributes to its rapid antidepressant effects. 3 In addition, it induces serotonin and dopamine release via multiple mechanisms, 12 regulates synaptic plasticity and forms excitatory synapses, resulting in an immediate response.13,14 It can be administered via intranasal, intravenous, intramuscular, and oral routes.
Various studies have also demonstrated a rapid and sustained improvement in depression and suicidal ideation or risk with ketamine therapy.8,10,15–21 While the majority of these studies have utilized the intravenous route of ketamine administration, which remains the most common method, it is often inconvenient, costly, and generally non-feasible in emergency settings, 22 compared to the oral route. Limited studies have emerged considering the role of oral ketamine in managing severe depression and suicidality, for example, a study by Kaur et al. 23 included 30 patients, while another study by Can et al. 24 included 32 patients. Kumar et al. 25 compared the efficacy of oral (n = 30) and intravenous ketamine (n = 31) in treatment-resistant depression (TRD) patients, and found better acceptability and tolerability of oral ketamine compared to the intravenous route.
Despite its potential as an effective and acceptable treatment for chronic or severe depression and active suicidal risk, only a few studies have examined the use of oral ketamine as presented in the literature. Thus, this retrospective study was conducted to assess the response of oral ketamine in patients with depression and suicidality.
Methods
This retrospective cross-sectional study was conducted at Institute of Mental Health and Neurosciences Kashmir (IMHANS-K), an associated hospital of Government Medical College, Srinagar. Data were collected from records between January and November 2024, following Institutional Review Board approval at Government Medical College, Srinagar (IRBGMC-SGR/PSY/850).
Ketamine is administered at IMHANS-K through oral and intravenous routes for patients diagnosed with major depressive disorder (MDD), bipolar disorder (depression), or in cases of suicidality, to provide prompt relief from severe depressive symptoms and mitigate suicide risk, following the acquisition of written informed consent. The diagnoses of MDD and bipolar disorder (depression) are based on criteria outlined in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). 26 Ketamine is administered every third day, with close monitoring of vital signs and any potential adverse effects. For oral administration, patients initially receive 150 mg, which may be gradually increased to 175 mg or 200 mg based on clinical response. In patients weighing less than 40 kg, the starting dose is 50 mg, with subsequent adjustments based on individual response.
Patients received structured psychoeducation and supportive counseling before, during, and after ketamine administration.
Before the Session
Patients were informed about the purpose of ketamine therapy, its rapid antidepressant and anti-suicidal potential, expected duration of effects, and possible side effects (e.g., dizziness, dissociation, nausea, hypertension). This pre-session dialogue aimed to reduce anxiety, set realistic expectations, and obtain informed consent.
During the Session
Patients were closely monitored for physiological and psychological responses. Psychiatrists provided reassurance and guidance to help patients cope with transient perceptual changes or dissociative experiences, maintaining a calm and supportive environment throughout the ingestion process.
After the Session
Post-session discussions focused on processing experiences, reinforcing adherence, and addressing concerns regarding side effects or mood changes. Psychiatrists also encouraged the reporting of delayed adverse effects and emphasized ongoing follow-up to monitor clinical response, thereby contributing to tolerability and retention.
All the study participants were already on psychotherapy, standard antidepressant or mood-stabilizing regimens appropriate to their diagnosis (e.g., Selective Serotonin Reuptake Inhibitor [SSRI]s, Serotonin and Norepinephrine Reuptake Inhibitor [SNRI]s, or lithium/valproate for bipolar depression) before initiating oral ketamine therapy. No major drug interactions were reported that required modification of existing treatment. However, ketamine dosing was carefully titrated based on clinical response and body weight, and patients were closely monitored for hemodynamic changes or additive sedative effects, particularly when concomitant psychotropic medications were in use.
Ketamine is dispensed from a vial containing 50 mg of ketamine per 1 mL. Depending on the patient’s preference, the ketamine can be mixed with 200 mL of fruit juice or water. The resulting mixture is then consumed in sips over 10–15 minutes. Our treatment procedure was based on practical considerations provided by Andrade 27 and used in other studies.23,25 The Hamilton Depression Rating Scale (HAMD) 28 and the Modified Scale for Suicidal Ideation (MSSI) 29 were used to assess depressive symptoms and the severity of suicidal thoughts, respectively. Previous studies have shown HAMD to be a reliable and valid measure of depression with good specificity and sensitivity. HAMD has been proven to be an appropriate and valid scale to measure depression30–32 with excellent inter-rater reliability in Indian settings.33,34 Similarly, MSSI is a reliable and valid instrument to assess suicidal ideation29,35 and has been utilized in an Indian setting. 23 These assessments were conducted at baseline, when the patient first presented to our institute, and again 24 hours later, to the third oral ketamine session administered by a psychiatrist.
The inclusion criteria for the study were as follows: (a) Patients aged >18 years, with a diagnosis of MDD or bipolar disorder (depression), according to DSM-5, 26 or exhibited any active suicidal ideation or risk (at the time of presentation at our institute); (b) patients must have received oral ketamine treatment between January 2024 and November 2024, with complete medical records available. After reviewing the records, we found that 46 patients received oral ketamine at our institute, all diagnosed with MDD or bipolar disorder (depression). However, five patients dropped out before their third ketamine session as they did not return for further follow-ups. Therefore, a total of 41 patients with complete medical records were included in the study. We retrieved the sociodemographic and clinical details of the 41 patients who completed the oral ketamine treatment from their medical records using a semi-structured proforma. Records with incomplete or missing information were excluded from the study.
We undertook the following measures to minimize potential sources of bias. We used predefined inclusion and exclusion criteria and included all consecutive patient records that met these criteria during the study period to reduce selection bias. Standardized and validated assessment tools (HAMD and MSSI) were used consistently to minimize measurement bias. Data extraction was performed using a uniform proforma to ensure consistency, and efforts were made to verify data accuracy through cross-checking with the other co-author. In addition, we adhered to the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines for transparent reporting of observational studies.
The data were analyzed using Stata version 17. Categorical and continuous variables were presented as percentages and means (with standard deviations [SD]), respectively. The normality of HAMD and MSSI scores was assessed using the Shapiro–Wilk test. A paired t-test was conducted to compare the differences in HAMD and MSSI scores before ketamine therapy and after the third session of ketamine therapy. A two-sample t-test was used to evaluate the differences in HAMD and MSSI across various variables. Two-sided p values of less than .05 were considered statistically significant.
Results
A total of 41 patients were included in this study. The mean ± SD age of subjects was 36.65 ± 12.34 years, with a predominance of female gender (65.9%). Patients with a diagnosis of MDD were the majority (N = 26; 63.4%). Mean of the first ketamine dose was 145.12 mg and 171.34 mg for the third dose. Dizziness (N = 8; 19.51%), hypertension (N = 8; 19.51%), and nausea (N = 8; 19.51%) were among the most common side effects reported by patients when they received ketamine therapy. Complete sociodemographic, clinical, and side effect profiles are presented in Tables 1 and 2, respectively.
The mean ± SD of HAMD before the ketamine session (HAMD1) was 24.07 + 4.18, and after the third dose (HAMD3) was 15.87 ± 4.36. Similarly, we noted a decrease in MSSI before the third ketamine session (MSSI1 = 11.12 + 6.18) and after the third ketamine session (MSSI3 = 6.17 ± 5.14). All of these were statistically significant (p < .001). The complete paired t-test analysis assessing the difference between HAMD and MSSI is presented in Table 3. Box plots of changes in HAMD and MSSI are presented in Figures 1 and 2, respectively.
Sociodemographic and Clinical Details of Subjects.
MDD: Major depressive disorder, BPAD: Bipolar affective disorder, HAMD: Hamilton depression rating scale, MSSI: Modified scale for suicidal ideation.
Side Effect Profile of Patients Who Received Oral Ketamine.
Paired t-test Showing Difference in HAMD and MSSI.
HAMD1: HAMD before oral ketamine session, HAMD3: HAMD after the third dose of oral ketamine, ∆HAMD: Change in HAMD score, MSSI: Modified scale for suicidal ideation, MSSI1: MSSI before oral ketamine session, MSSI3: MSSI after the third dose of oral ketamine, ∆MSSI: Change in MSSI score.
BOX PLOT SHOWING CHANGES IN HAMD.
BOX PLOT SHOWING CHANGES IN MSSI.
Married patients showed the greatest reductions in HAMD (mean = −8.89; p = .04) and MSSI (mean = −5.58; p = .01), as assessed by a two-sample t-test. Whereas, individuals residing in urban areas showed a significant improvement in HAMD, with a mean reduction of 9.00 points (p value = .03). The remaining two-sample t-test results across variables are presented in Table 4.
Two-sample t-test Among Different Variables.
MDD: Major depressive disorder, BPAD: Bipolar affective disorder, HAMD: Hamilton depression rating scale, MSSI: Modified scale for suicidal ideation.
Discussion
This retrospective study aimed to evaluate the efficacy of oral ketamine in managing depression and suicidality, particularly among patients diagnosed with MDD and bipolar affective disorder (BPAD) depression. Our findings indicate that oral ketamine significantly reduces depressive symptoms, as measured by the HAMD, and suicidal ideation, assessed using the MSSI. Specifically, we observed a substantial reduction in both HAMD and MSSI scores after three sessions of oral ketamine therapy, administered on three alternate-day sessions.
Numerous studies have clearly highlighted the antidepressant and anti-suicidal properties of intravenous ketamine. However, there is a lack of research on oral ketamine in our country, and none from our region. In an outpatient setting, where managing suicidality and severe depressive symptoms is crucial, intravenous ketamine often remains impractical due to its invasive nature and the need for anesthesia. Therefore, the oral route may present a better alternative for this population.
Irwin et al. 36 conducted a retrospective study among 14 palliative care patients and found significant improvement in comorbid depression and anxiety symptoms with oral ketamine at a dose of 0.5 mg/kg as measured by the Hospital Anxiety and Depression Scale. Previous studies have explored oral ketamine as an antidepressant and anti- suicidal agent. Similarly, Lara et al. 37 has administered 10 mg of oral ketamine sublingually to 26 refractory depression patients, reporting significant improvement in 75% patients.
Shirawi et al. 38 in an open-label case series conducted among 22 patients, oral ketamine capsules were safe and well-tolerated, and approximately only 30% reported some clinical benefit. A double blind randomized controlled trial (RCT) by Arabzadeh et al. 39 highlighted significant improvement with the oral ketamine group (45 patients) as measured by HAMD, without any notable side effects. Domany et al. 40 administered oral ketamine at a dose of 1 mg/kg to 22 patients suffering from TRD and reported a significant mean reduction of 12.75 in Montgomery–Åsberg Depression Rating Scale (MADRS) scores at day 21. Can et al. 24 administered oral ketamine (0.5–3 mg/kg) among 32 chronic suicidal patients and reported approximately 69% reduction in suicidality after six weeks of treatment.
From India, Kaur et al. 23 administered oral ketamine at a fixed dose of 150 mg in three alternate-day sessions among 30 severely depressed patients, and reported a significant reduction in MADRS (28.8–21.9) and MSSI (25.1–17.3) scores. Our results showed a significant improvement in depressive symptoms, which can be attributed to our method of dose escalation during the second and third oral ketamine sessions, setting us apart from other studies. It is important to note that we used a different scale to assess depressive symptoms, the HAMD. Another study by Kumar et al. 25 compared the efficacy of intravenous and oral ketamine in patients with TRD. Oral ketamine (N = 30) was administered at a dosage of 150 mg in 50 mL of water, over 15 minutes, and intravenous ketamine (N = 31) was administered at a dosage of 0.5 mg/kg, for 40 minutes. Although they reported no significant difference between the oral and intravenous groups, overall, fewer dropouts and better tolerability were observed in the oral ketamine group. Another interesting RCT by Colla et al. 41 examined the role of prolonged-release oral ketamine in 27 patients with TRD, who reported a non-significant reduction in MADRS scores after treatment.
Our study found a mean reduction in HAMD scores of 8.19 (from 24.07 to 15.87) and a 4.95-point decrease in MSSI scores (from 11.12 to 6.87). Both reductions were statistically significant (p value < .001). These results are consistent with previous research that highlights ketamine’s rapid antidepressant and anti-suicidal effects. This is attributed to its unique mechanisms of action, including NMDA receptor antagonism and enhanced synaptic plasticity. Additional mechanisms may involve downregulation of AMPA receptors in the prefrontal cortex and hippocampus, activation of the mammalian target of rapamycin pathway, inhibition of glycogen synthase kinase-3, and the involvement of the kynurenine pathway. Together, these factors contribute to the rapid antidepressant and anti-suicidal effects of ketamine. 3
Notably, married individuals and those residing in urban areas showed the greatest reductions in depressive symptoms and suicidal ideation. Married individuals had a mean decrease of 8.89 (p value = .04), compared with 6.50 in unmarried individuals. Also, married individuals had a greater reduction in MSSI of 5.58 (p = .01) than unmarried individuals (6.50). It could be attributed to the benefits of enhanced social and emotional support. Furthermore, the presence of a supportive partner could facilitate timely medical intervention, improve treatment adherence, and reduce perceived loneliness, all of which contribute to better outcomes for married individuals. 42 This aligns with the social-buffering hypothesis, whereby strong interpersonal ties mitigate the impact of stressors on mental health 43 and findings that perceived social support mediates the benefits of marriage for psychological wellbeing. 44
Similarly, subjects residing in urban areas showed a greater decline in mean HAMD score of 9.00 points. Urban residents, on the other hand, experienced more significant decreases in depressive symptoms compared to those residing in rural areas, likely due to easy access to mental health facilities, timely follow-up care, and reduced logistical challenges in urban areas, which may enable better adherence to treatment regimens. In contrast, rural residents often face barriers such as limited access to healthcare, social isolation, and economic hardship, which may impede recovery and reduce treatment efficacy.45–48 These disparities highlight the influence of environmental and socioeconomic factors on treatment outcomes.
There was no significant difference in outcome based on gender or diagnosis (MDD vs. BPAD depression). Reports on gender-specific differences in ketamine response are mixed. Previous studies have reported broadly similar antidepressant response rates in males and females,49–51 while a preclinical and mechanistic study indicates possible sex-dependent pharmacodynamic and metabolic differences that warrant further study. 52 Ponton et al. 52 emphasized that hormones such as estrogen and progesterone in females may influence a greater response to ketamine in depression cases. This may be due to a smaller sample size, or it may indicate that the efficacy of oral ketamine is consistent across these subgroups, broadening its potential applicability. Our finding of no subgroup differences should be interpreted cautiously; larger prospective studies are needed to confirm whether the efficacy of oral ketamine generalizes across these patient groups.
Side effects such as dizziness, hypertension, and nausea were reported by 19.51% of our patients, which aligns with the known adverse effects of ketamine. Additionally, dissociation—a common side effect of ketamine—was observed in 17.07% of our patients. This side effect was generally well-tolerated and did not require discontinuation of treatment. This tolerance may be attributed to effective counseling provided to patients regarding common side effects, reassuring them that these temporary effects would subside. Notably, the dropout rate was relatively low, with only five patients not completing three ketamine sessions; however, the exact reasons for their discontinuation remain unclear.
The significant reductions in HAMD and MSSI scores within a short timeframe highlight oral ketamine as a viable option for managing severe depression and suicidality in emergency settings. Its ease of administration, cost- effectiveness, and rapid onset of action make it a practical alternative to intravenous ketamine and other time-intensive therapies, such as ECT. Nevertheless, close monitoring of side effects and careful patient selection are essential, along with psychoeducation about the potential temporary side effects.
Limitations
First, it relies on previously recorded data as a retrospective study, which may introduce biases related to inconsistent documentation. Detailed records of HAMD and MSSI scores for each ketamine session were not consistently available. Although all case files contained baseline and post-third-session assessments, analysis was restricted to these time points, which may limit the ability to observe dose-wise trends in symptom improvement. Second, the sample size was not calculated before the conduct of the study and was small, which limits the generalizability of the findings to larger or more diverse populations. Third, the absence of a control group prevents us from directly comparing the efficacy of oral ketamine with other treatment modalities, such as intravenous ketamine or standard antidepressant therapies. Although we attempted to include additional clinically relevant variables such as atypical or melancholic features, Body mass index (BMI), anxious depression, Clinical Global Impression (CGI) scores, previous use of ketamine or ECT, and prior antidepressant failures, these details were not consistently available across all case records, which limited further analysis. Also, the absence of a standardized checklist for assessing ketamine-induced adverse drug reactions and reliance on documentation by different treating psychiatrists may have introduced variability and underreporting of mild or transient effects. Furthermore, the study did not evaluate the long-term outcomes of oral ketamine treatment, leaving its sustained efficacy in managing depression and suicidality unclear. Final, the single-center design of this study may restrict its applicability to other settings, especially those with differing cultural, socioeconomic, or healthcare delivery contexts. Future studies with larger sample sizes, prospective designs, and long-term follow-up are recommended to address these gaps and validate the findings.
Conclusion
Oral ketamine appears to be a promising and effective treatment for patients with severe depression and suicidality, offering rapid symptom relief with good tolerability. These findings support its role as an adjuvant or alternative to conventional antidepressants and other interventions, such as ECT, particularly in resource- limited or emergency settings. However, the results should be interpreted with caution due to the retrospective design and limited sample size. Future research should focus on employing robust, prospective, and controlled study designs to determine optimal dosing strategies, evaluate long-term safety, and establish sustained efficacy, thereby strengthening the evidence base for clinical use of ketamine in depression.
Supplemental Material
Supplemental material for this article is available online.
Footnotes
Availability of Data and Materials
The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.
Consent for Publication
Not applicable.
Declaration of Conflicting Interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Declaration Regarding the Use of Generative AI
None used.
Ethics Approval and Consent to Participate
The study was approved by the Institutional Review Board of Government Medical College, Srinagar, Jammu and Kashmir, India (IRB-GMC-SGR/PSY/850; dated 16 November 2024). Informed Consent was taken from all the participants before therapy.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
References
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