The pain drug generating the most excitement in psychiatric research is ketamine, a decades-old anesthetic and analgesic now at the center of a serious effort to treat depression that refuses to respond to conventional medications. In January 2025, the FDA approved esketamine — a nasal spray derivative of ketamine sold as Spravato — as the first and only standalone monotherapy for adults with treatment-resistant depression, a milestone that confirmed what researchers had been observing for years: drugs originally designed to manage pain can rapidly lift severe depression in ways that traditional antidepressants simply cannot. Ketamine is not alone in this space. Several other pain-related compounds, including formulations derived from buprenorphine and methadone, have entered clinical trials targeting the same patient population, with mixed but sometimes remarkable results.
Treatment-resistant depression affects roughly 30 percent of people diagnosed with major depressive disorder, meaning millions of patients cycle through multiple medications without meaningful relief. For these individuals, the standard playbook of SSRIs, SNRIs, and augmentation strategies has failed. The emergence of pain drugs as psychiatric tools represents a genuine paradigm shift — these compounds act on entirely different brain pathways, particularly the glutamate system, and can produce antidepressant effects within hours rather than the weeks required by conventional medications. For families navigating dementia care, where depression frequently co-occurs and complicates cognitive decline, the implications are significant. This article covers the FDA-approved ketamine derivative now available in clinics, a promising oral ketamine tablet that could bring treatment home, the opioid-based compounds that have stumbled in late-stage trials, and the underlying brain science that explains why pain drugs work on depression at all.
Table of Contents
- Why Is a Pain Drug Being Studied for Treatment-Resistant Depression?
- What Is Spravato, and What Do the Clinical Trial Numbers Actually Show?
- Could an Oral Ketamine Tablet Change Everything?
- What Happened to the Opioid-Based Approaches?
- Low-Dose Buprenorphine — Promise in Older Adults, but Serious Caveats
- What This Means for Dementia Caregivers and Brain Health
- Where the Research Goes From Here
- Conclusion
- Frequently Asked Questions
Why Is a Pain Drug Being Studied for Treatment-Resistant Depression?
The connection between pain medications and depression is not as strange as it sounds. Ketamine was synthesized in 1962 as a surgical anesthetic, and for decades it was used primarily in operating rooms and emergency departments to manage acute pain. But in 2000, a small study at Yale demonstrated something unexpected: a single low-dose intravenous infusion of ketamine — approximately 0.5 mg/kg — produced rapid antidepressant effects in patients who had not responded to other treatments. The results were dramatic enough that they launched an entirely new field of research. Unlike SSRIs, which modulate serotonin and take four to six weeks to show benefit, ketamine blocks NMDA (N-methyl-D-aspartate) glutamate receptors, triggering rapid increases in synaptic plasticity and neurotrophic factors that can relieve depressive symptoms within hours. This mechanism matters because it represents a fundamentally different approach to treating depression. Traditional antidepressants work on the monoamine system — serotonin, norepinephrine, dopamine.
Ketamine and its derivatives work on the glutamate system, which is the brain’s primary excitatory neurotransmitter network and plays a central role in learning, memory, and neural connectivity. For patients whose depression has not responded to monoamine-based drugs, targeting a completely different system offers a genuine alternative rather than another variation on the same theme. The speed of onset is equally important: when someone is in a depressive crisis, waiting six weeks for a medication to potentially work is not just inconvenient — it can be dangerous. Other pain drugs have entered this research space because they also interact with brain receptors involved in mood regulation. Buprenorphine, an opioid used to treat chronic pain and opioid addiction, acts on mu-opioid and kappa-opioid receptors that influence emotional processing. Esmethadone, derived from methadone, targets NMDA receptors much like ketamine but with far lower opioid activity. The common thread is that these compounds were developed for pain but turned out to have psychiatric effects that could not be ignored.
What Is Spravato, and What Do the Clinical Trial Numbers Actually Show?
Spravato (esketamine) nasal spray, manufactured by Janssen (a Johnson & Johnson subsidiary), is currently the most established ketamine-based treatment for depression. The FDA first approved it in 2019 as an add-on to oral antidepressants for treatment-resistant depression, but the more significant regulatory milestone came on January 21, 2025, when the FDA approved Spravato as a standalone monotherapy — meaning patients no longer need to take a traditional antidepressant alongside it. This made Spravato the first and only monotherapy specifically approved for adults with treatment-resistant depression. The pivotal monotherapy trial demonstrated that 22.5 percent of patients receiving Spravato alone achieved full remission at four weeks, compared with 7.6 percent on placebo. The effect sizes were 0.48 for the 56 mg dose and 0.63 for the 84 mg dose — numbers that are considered clinically meaningful in psychiatric research, where effect sizes for many approved antidepressants hover around 0.3. However, these numbers also reveal an important limitation: nearly 78 percent of patients on Spravato did not achieve remission at the four-week mark. Spravato is not a cure, and it does not work for everyone.
It is a meaningful advance for a subset of patients who have exhausted other options. There are also practical barriers. Spravato must be administered in a certified healthcare setting — a doctor’s office or clinic — where the patient is monitored for at least two hours after each dose. This requirement exists because the drug carries real risks: sedation, dissociation (a feeling of detachment from reality), respiratory depression, and potential for misuse. It remains a Schedule III controlled substance. For older adults, particularly those with cardiovascular concerns common in dementia caregiving populations, the transient blood pressure increases associated with Spravato require careful clinical assessment. This is not a medication that patients pick up at the pharmacy and take at home — at least not yet.
Could an Oral Ketamine Tablet Change Everything?
One of the most promising developments in this field is R-107, an extended-release oral ketamine tablet being developed for at-home use. The BEDROC Phase 2 trial, published in Nature Medicine in June 2024, tested these tablets in 231 patients with treatment-resistant depression and produced striking results: approximately 73 percent of patients responded after just one week of daily 120 mg doses. To put that response rate in context, most antidepressant trials consider a 50 percent response rate a strong outcome. What makes R-107 particularly noteworthy is not just its efficacy but its tolerability profile. One of the major drawbacks of IV ketamine infusions and intranasal Spravato is the constellation of side effects — dissociation, sedation, and blood pressure spikes — that require clinical monitoring. The extended-release oral formulation in the BEDROC trial showed minimal dissociation, sedation, or blood pressure increases when dosed twice weekly over 12 weeks.
Study investigator Paul Glue noted that a well-tolerated tablet form could allow at-home dosing, which would dramatically expand patient access. For the millions of people with treatment-resistant depression who live far from ketamine clinics or cannot manage twice-weekly trips to a medical office, this would be transformative. However, Phase 2 results do not guarantee Phase 3 success — a reality that other drugs in this space have demonstrated painfully. The BEDROC trial was relatively small, and larger confirmatory trials will need to replicate these findings before the FDA considers approval. The history of psychiatric drug development is littered with compounds that looked excellent in early trials and then failed in the larger, more rigorous studies required for regulatory approval. Cautious optimism is warranted, but patients and clinicians should temper expectations until Phase 3 data are in hand.
What Happened to the Opioid-Based Approaches?
While ketamine-based treatments have progressed, several opioid-derived compounds have struggled to cross the finish line. The most prominent example is ALKS-5461, developed by Alkermes, which combined buprenorphine (a partial opioid agonist used for pain and addiction) with samidorphan (an opioid antagonist designed to block the euphoric effects and reduce abuse potential). The theory was sound: buprenorphine’s activity at kappa-opioid receptors could address the anhedonia and emotional blunting central to treatment-resistant depression, while samidorphan would keep the drug from being addictive. ALKS-5461 received FDA Fast Track Designation in October 2013, signaling early regulatory enthusiasm. But the clinical trial results told a more complicated story. In the FORWARD-5 trial, which enrolled approximately 800 adults across more than 100 sites, two of three Phase 3 trials failed to meet their primary endpoints. In November 2018, an FDA advisory panel voted against recommending approval, finding the evidence insufficient.
The FDA formally rejected the drug in 2019. The failure illustrates a recurring challenge in psychiatric drug development: depression is a heterogeneous condition, and a drug that helps some patients enormously may show only modest effects when averaged across a large, diverse trial population. A similar fate befell esmethadone (REL-1017), derived from methadone but engineered with roughly 20-fold lower potency at the mu-opioid receptor to reduce abuse risk. Esmethadone acts primarily as an NMDA receptor antagonist, similar to ketamine. A Phase 2 trial in 62 patients with treatment-resistant depression showed promising efficacy, but the Phase 3 trial did not meet its primary endpoint — the mean difference versus placebo was just 2.3 points on the depression scale, with a p-value of 0.154 and an effect size of only 0.21. These numbers fell well short of statistical significance. The trajectory from encouraging Phase 2 data to disappointing Phase 3 results is a pattern that underscores why large, well-controlled trials remain the gold standard before any drug reaches patients.
Low-Dose Buprenorphine — Promise in Older Adults, but Serious Caveats
Despite the failure of ALKS-5461 as a combination product, research into low-dose buprenorphine alone continues to generate intriguing data, particularly in older adults — a population with direct relevance to dementia care. In studies of mid-life and older adults with treatment-resistant depression, low-dose buprenorphine produced a 60.7 percent reduction in average depression scores, from 28.1 to 10.7 on a standard rating scale. These were patients who had previously failed an average of 7.6 antidepressants — among the most treatment-resistant individuals in psychiatric research. The NIMH-funded IRLGRey-B trial further investigated this approach, randomizing 85 participants aged 50 and older with treatment-resistant depression to either buprenorphine augmentation or placebo for eight weeks. This trial specifically targeted an age group where depression frequently coexists with cognitive decline and early dementia, making the findings particularly relevant for brain health.
Late-life depression is both a risk factor for dementia and a condition that worsens its progression, so effective treatments carry implications beyond mood alone. The obvious concern with any opioid-based psychiatric treatment is the risk of dependence, even at low doses. Buprenorphine has a ceiling effect on respiratory depression that makes it safer than full opioid agonists, but it still carries dependence liability with prolonged use. For older adults who may already be managing complex medication regimens, adding an opioid — even a partial agonist at a low dose — introduces risks that must be weighed against the severity of the depression being treated. This is not a first-line or second-line approach; it is a strategy being explored for patients who have truly exhausted alternatives.
What This Means for Dementia Caregivers and Brain Health
Depression among dementia caregivers is staggeringly common — studies estimate that 30 to 40 percent of family caregivers experience clinically significant depression, and a substantial subset do not respond adequately to standard antidepressants. For these individuals, the development of faster-acting treatments with novel mechanisms is not abstract pharmaceutical news. A caregiver who has cycled through three or four medications over several months without relief faces a compounding crisis: their own declining mental health diminishes their capacity to provide care, which in turn worsens outcomes for the person with dementia.
The rapid onset of ketamine-based treatments — measurable improvement within hours to days rather than weeks — could be particularly valuable in caregiving contexts where every week of untreated depression has cascading consequences. At the same time, the logistical demands of current Spravato treatment (in-clinic administration with two-hour monitoring) may be impractical for caregivers who cannot easily leave the person in their care. The development of a tolerable oral ketamine tablet would address this barrier directly, though patients should discuss any new psychiatric treatment with their physician, especially when managing the overlapping health needs common in dementia care settings.
Where the Research Goes From Here
The next few years will be decisive for this class of treatments. The R-107 extended-release ketamine tablet faces Phase 3 trials that will determine whether the impressive Phase 2 results can be replicated at scale. If successful, it could become the first at-home ketamine treatment for depression, removing the clinical-setting requirement that currently limits access to Spravato. Meanwhile, researchers continue to investigate whether ketamine’s effects on synaptic plasticity might have neuroprotective properties relevant to cognitive decline — a hypothesis that, if supported, would place these drugs at the intersection of depression treatment and dementia prevention.
The broader lesson from this research is that the traditional boundaries between drug categories are dissolving. A pain drug becomes a psychiatric treatment. An anesthetic becomes a tool for emotional recovery. The science is following the biology rather than the labels, and for the millions of people living with depression that has not responded to conventional treatment, that willingness to look beyond established categories may ultimately be what provides relief.
Conclusion
Ketamine’s journey from operating room anesthetic to psychiatric breakthrough represents one of the most significant shifts in depression treatment in decades. The FDA’s 2025 approval of Spravato as a standalone monotherapy for treatment-resistant depression validated years of research, while the BEDROC trial’s oral ketamine results suggest that at-home treatment could be within reach. At the same time, the failures of ALKS-5461 and esmethadone serve as reminders that promising early data does not always survive the rigor of large-scale trials. For every compound that advances, others fall short.
For patients and caregivers navigating treatment-resistant depression — particularly in the context of dementia care and brain health — these developments warrant close attention but not premature action. Spravato is available now through certified clinics for qualifying patients. Oral ketamine tablets and other novel compounds remain investigational. The most important step for anyone considering these options is a thorough conversation with a psychiatrist who is current on the rapidly evolving evidence, and who can weigh the potential benefits against the real risks of sedation, dissociation, and in the case of opioid-based treatments, dependence.
Frequently Asked Questions
Is ketamine the same as the party drug Special K?
Ketamine is the same compound, but medical ketamine for depression is administered at carefully controlled low doses — typically around 0.5 mg/kg intravenously or via nasal spray — in supervised clinical settings. The doses and context are fundamentally different from recreational misuse, though the shared identity is one reason ketamine treatments carry regulatory restrictions and require in-office monitoring.
Can I get Spravato from my regular doctor?
No. Spravato can only be administered in healthcare settings certified under the Spravato REMS (Risk Evaluation and Mitigation Strategy) program. You cannot fill a prescription at a pharmacy and take it at home. Each session involves nasal spray administration followed by at least two hours of monitoring for sedation, dissociation, and blood pressure changes.
How fast does ketamine work for depression compared to regular antidepressants?
Ketamine and its derivatives can produce measurable antidepressant effects within hours to days, compared to four to six weeks for most SSRIs and SNRIs. In the BEDROC Phase 2 trial, approximately 73 percent of patients responded after just one week. However, the effects of a single ketamine dose can be temporary, and ongoing treatment is typically needed to sustain improvement.
Is treatment-resistant depression common in older adults and dementia patients?
Yes. Depression affects an estimated 30 to 40 percent of dementia caregivers and is frequently seen in people with early cognitive decline. Late-life depression is both a risk factor for developing dementia and a condition that accelerates its progression. Treatment resistance is particularly common in this population due to the complex interplay of neurological changes, medication interactions, and psychosocial stressors.
Are there risks to using opioid-based depression treatments in older adults?
Yes. Even low-dose buprenorphine carries dependence liability with prolonged use, and older adults may be more susceptible to side effects including sedation, falls, and respiratory effects. Any opioid-based psychiatric treatment in this population requires careful monitoring and should only be considered after multiple conventional treatments have failed.
Will oral ketamine tablets be available soon?
Not immediately. The R-107 extended-release tablets showed strong Phase 2 results published in 2024, but Phase 3 trials are still needed. If those trials succeed and regulatory review proceeds smoothly, approval could still be several years away. Patients interested in ketamine treatment today should discuss currently available options — including Spravato and off-label IV ketamine — with their psychiatrist.
