Newest Antidepressants: Brexanolone, Esketamine, Agomelatine

Why These Newer Antidepressants Matter

Most familiar antidepressantsincluding selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors, and older tricyclic drugsalter monoamine signaling. They can be effective, but improvement may take several weeks, side effects sometimes limit treatment, and a substantial group of patients does not respond adequately to the first medication tried.

These three drugs expanded the antidepressant conversation in different ways:

• Brexanolone demonstrated that a neuroactive steroid could rapidly improve postpartum depression.
• Esketamine introduced an FDA-approved glutamate-based treatment for treatment-resistant depression.
• Agomelatine offered a circadian-focused approach built around melatonin and serotonin receptors.

None is a universal replacement for standard antidepressants. They are specialized tools, and one of them is no longer commercially available in the United States. Psychiatry, like a well-stocked toolbox, benefits from optionsbut a hammer remains a poor choice for tightening every screw.

Brexanolone: A Historic Treatment for Postpartum Depression

What Is Brexanolone?

Brexanolone is an intravenous formulation of allopregnanolone, a naturally occurring neuroactive steroid derived from progesterone. It was sold under the brand name Zulresso and became the first medication specifically approved by the FDA for postpartum depression in adults in 2019.

Postpartum depression is more than temporary sadness or the so-called baby blues. It can involve persistent low mood, anxiety, guilt, loss of pleasure, disrupted sleep beyond what infant care explains, difficulty bonding, impaired functioning, and thoughts of self-harm. Symptoms may begin during pregnancy or after delivery.

How Brexanolone Works

Allopregnanolone levels rise during pregnancy and fall sharply after childbirth. Researchers have studied whether difficulty adapting to this hormonal shift may contribute to postpartum depression in susceptible individuals.

Brexanolone positively modulates GABA-A receptors. GABA is the brain’s principal inhibitory neurotransmitterthe chemical equivalent of asking an overexcited nervous system to use its indoor voice. By enhancing GABA-A signaling, brexanolone was designed to help restore balance in neural networks affected during the perinatal period.

How It Was Administered

Brexanolone was not a medication patients could pick up at a pharmacy and take between diaper changes. It required a continuous intravenous infusion lasting approximately 60 hours in a certified medical setting.

Patients needed close supervision, continuous pulse-oxygen monitoring, and assistance when interacting with their children. The FDA-mandated restricted-distribution program existed because treatment could cause profound sedation or sudden loss of consciousness.

Benefits and Limitations

Clinical studies found that some patients experienced meaningful reductions in postpartum depression symptoms by the end of the infusion, with benefits observed much sooner than would normally be expected from a conventional oral antidepressant. Follow-up results suggested that improvement could persist for several weeks in some participants.

The practical burden was substantial, however. A multiday hospital or treatment-center stay, specialized staffing, insurance authorization, childcare arrangements, travel, and cost all complicated access. The treatment was scientifically exciting but logistically about as casual as moving apartments during a thunderstorm.

Is Brexanolone Still Available?

No. The manufacturer ended commercial availability after December 31, 2024. At the company’s request, the FDA formally withdrew approval of Zulresso effective April 14, 2025 because it was no longer marketed.

This does not mean the FDA suddenly concluded that brexanolone was ineffective or discovered a new hidden danger. The withdrawal followed a commercial decision. Its scientific legacy remains important because it validated neuroactive-steroid treatment for postpartum depression and helped pave the way for zuranolone, an oral neuroactive steroid approved for postpartum depression in 2023.

Esketamine: A Rapid-Acting Option for Resistant Depression

What Is Esketamine?

Esketamine is the S-enantiomer, or one molecular form, of ketamine. It is marketed as the nasal spray Spravato and is classified as a Schedule III controlled substance in the United States.

The FDA initially approved esketamine in 2019 for adults with treatment-resistant depression when used with an oral antidepressant. In January 2025, its treatment-resistant depression indication expanded to include monotherapy, meaning it may now be used without a separate oral antidepressant when clinically appropriate.

It is also approved, together with an oral antidepressant, for depressive symptoms in adults with major depressive disorder accompanied by acute suicidal ideation or behavior. That indication does not mean the medication has been proven to prevent suicide or eliminate suicidal thinking. Emergency evaluation, safety planning, hospitalization when needed, psychotherapy, and ongoing clinical care remain essential.

How Esketamine Works

Unlike SSRIs, esketamine does not primarily work by increasing serotonin. It antagonizes NMDA receptors involved in glutamate signaling. The downstream effects are believed to influence synaptic plasticitythe brain’s ability to strengthen, weaken, and reorganize connections.

This different mechanism may explain why symptom improvement can begin within hours or days for some patients. Conventional antidepressants often require several weeks before their full effect becomes clear.

Rapid does not mean magical. Some patients improve dramatically, some improve modestly, and others do not respond. Depression remains stubbornly uninterested in one-size-fits-all marketing.

What an Esketamine Session Involves

Esketamine cannot be taken home. Patients self-administer the nasal spray under supervision at a healthcare facility certified through the Spravato Risk Evaluation and Mitigation Strategy program.

A common treatment-resistant depression schedule begins with sessions twice weekly for four weeks. Treatment may then decrease to once weekly, followed by once weekly or once every two weeks during maintenance. The exact dose, frequency, and duration depend on response, tolerability, prescribing information, and the clinician’s judgment.

After each dose, patients are monitored for at least two hours. Blood pressure and mental status are checked, and patients must arrange transportation home. Driving, operating machinery, or making a heroic attempt to reorganize the garage is generally postponed until the following day after restful sleep.

Side Effects and Safety Concerns

Common esketamine side effects include:

• Dissociation or feeling detached from oneself or the environment
• Dizziness, vertigo, or a floating sensation
• Sedation and fatigue
• Nausea or vomiting
• Anxiety or temporary perceptual changes
• Increased blood pressure
• An altered or unpleasant taste

Its boxed warning addresses sedation, dissociation, respiratory depression, abuse or misuse, and suicidal thoughts and behaviors associated with antidepressant treatment in younger patients. Clinicians also screen for conditions that could make temporary blood-pressure increases especially dangerous.

Esketamine may be considered when multiple adequate antidepressant trials have failed, but it is not merely an extra-strength nasal spray. It is a structured clinical treatment requiring screening, supervision, monitoring, and follow-up.

Agomelatine: Depression Treatment Through the Body Clock

What Is Agomelatine?

Agomelatine is an atypical oral antidepressant marketed in parts of Europe and other international markets under names such as Valdoxan. It is approved in the European Union for major depressive episodes in adults but is not approved or marketed in the United States.

American patients should not purchase agomelatine from unverified online sources. Products sold through unauthorized websites may be counterfeit, incorrectly dosed, contaminated, or supplied without the liver monitoring required for safe prescribing.

How Agomelatine Works

Agomelatine acts as an agonist at MT1 and MT2 melatonin receptors and as an antagonist at 5-HT2C serotonin receptors. Its melatonin-receptor activity may help resynchronize circadian rhythms, while 5-HT2C blockade may increase norepinephrine and dopamine release in parts of the prefrontal cortex.

This mechanism makes agomelatine particularly interesting when depression includes disrupted sleep timing, early-morning waking, poor sleep quality, or a body clock that appears to have thrown its schedule into a blender.

Agomelatine is generally taken at bedtime in countries where it is approved. It does not work like an ordinary sleeping pill, and improved sleep does not necessarily equal full recovery from depression. Mood, motivation, cognition, anxiety, appetite, functioning, and safety still require assessment.

How Effective Is Agomelatine?

Some trials and meta-analyses have found agomelatine more effective than placebo and broadly comparable with established antidepressants. It has also been associated in some studies with fewer sexual side effects, less weight gain, and fewer discontinuation symptoms than certain serotonin-based drugs.

The evidence is not spotless. Independent reviews have raised concerns about publication bias, inconsistent trial results, and whether average benefits over placebo are large enough to be clinically important. The fairest conclusion is not that agomelatine is a miracle drug or a useless one. It appears to be a legitimate antidepressant option in countries where it is approved, but it has not consistently demonstrated superior overall efficacy.

The Major Concern: Liver Injury

Agomelatine can elevate liver enzymes and, rarely, cause serious liver injury. European product guidance therefore requires liver-function testing before treatment and at scheduled points during therapy, commonly around weeks 3, 6, 12, and 24, as well as after a dose increase when applicable.

It should not be started when liver enzymes exceed specified limits or in patients with active liver disease or hepatic impairment. Strong CYP1A2 inhibitors, including fluvoxamine and ciprofloxacin, can markedly increase agomelatine exposure and must not be combined with it under European prescribing guidance.

Possible warning signs of liver injury include yellowing of the skin or eyes, dark urine, pale stools, unexplained fatigue, loss of appetite, or pain in the upper-right abdomen. These symptoms require prompt medical attention.

Brexanolone vs. Esketamine vs. Agomelatine

How Clinicians Choose Among New Depression Treatments

Medication selection involves more than asking which drug is newest. A clinician considers the type and severity of depression, previous treatments, medical conditions, pregnancy or postpartum status, bipolar-spectrum symptoms, substance-use history, suicidal risk, medication interactions, treatment access, insurance coverage, and patient preferences.

Before labeling depression “treatment resistant,” clinicians may also confirm that previous medications were taken at therapeutic doses for adequate periods. They may assess adherence, thyroid disease, sleep apnea, anemia, substance use, trauma, medication side effects, and possible bipolar disorder. A treatment cannot fairly be called a failure when it never received a proper trialor when the original diagnosis needs revision.

Psychotherapy, exercise, sleep treatment, social support, transcranial magnetic stimulation, electroconvulsive therapy, and other interventions may be combined with or considered instead of medication. The best plan is rarely the flashiest plan. It is the one that is safe, evidence-based, accessible, and realistic enough to follow.

Realistic Treatment Experiences: What Patients May Encounter

The following scenarios are educational composites based on common treatment logistics and reported experiences. They are not testimonials from identifiable patients and should not be interpreted as predictions of individual results.

Experiencing a Multiday Brexanolone Infusion

When brexanolone was available, preparing for treatment could feel like coordinating a short hospital admission rather than starting a prescription. A postpartum patient might first complete psychiatric and medical evaluations while the treatment center sought insurance authorization. Family members could need to arrange childcare, transportation, time away from work, and help after discharge.

During the infusion, nurses monitored oxygen levels, alertness, blood pressure, and other vital signs. The patient could rest, eat, talk with family, or interact with the baby while another responsible adult was present. Some patients reported improvement during the infusion, describing a reduction in emotional heaviness or anxiety. Others experienced more gradual or limited change.

Even when symptoms improved quickly, follow-up care remained necessary. Brexanolone did not erase sleep deprivation, relationship stress, feeding challenges, trauma, or every biological and social contributor to postpartum depression. Medication could open a door, but recovery still required walking through it with support.

What an Esketamine Appointment May Feel Like

An esketamine session usually begins more routinely. The patient arrives at a certified clinic, reviews symptoms and side effects, and has blood pressure checked. After receiving instructions, the patient administers the nasal-spray devices several minutes apart.

Within a short period, ordinary sensations may feel unusual. The room might seem distant, time may feel stretched, or the patient may feel briefly separated from the body. Some people find the experience calm or neutral; others find it strange or anxiety-provoking. Clinics may provide a reclining chair, reduced lighting, an eye mask, or quiet music, although procedures vary.

The intense effects usually diminish during observation. Because dizziness, sedation, and impaired judgment can persist, the patient needs a ride home and should keep the remainder of the day uncomplicated. Scheduling twice-weekly induction visits around employment and family life can be one of the treatment’s biggest obstacles.

Response is not always cinematic. Improvement may appear as getting out of bed earlier, answering a neglected message, preparing a meal, or noticing that hopeless thoughts feel less convincing. Clinicians often use standardized symptom scales because meaningful progress can be subtle before it becomes obvious.

Living With an Agomelatine Monitoring Schedule

In a country where agomelatine is approved, the experience resembles taking a conventional daily antidepressantwith an important laboratory-testing subplot. Before prescribing it, the clinician reviews liver disease, alcohol intake, other medications, and baseline liver-function results.

The tablet is generally taken at bedtime. Some patients notice earlier improvements in sleep timing or sleep quality, while mood and motivation may take longer. Others experience headache, dizziness, nausea, unusual dreams, sleepiness, or no meaningful benefit.

Scheduled blood tests are not optional administrative decoration. They are a central part of safe treatment. A patient who dislikes needles may find this inconvenient, but skipping monitoring defeats one of the principal safeguards against significant liver injury.

The Shared Experience: Hope With Guardrails

What links these treatments is not a guarantee of rapid recovery. It is the possibility of helping selected patients through mechanisms outside the traditional antidepressant playbook. That possibility can feel hopeful, especially after several unsuccessful treatments.

Hope works best with guardrails. Patients still need accurate diagnosis, realistic expectations, safety monitoring, and a plan for what happens if treatment works only partlyor not at all. A new mechanism may change the route, but good psychiatric care still requires a careful driver, a reliable map, and occasional stops to check whether everyone is heading in the right direction.

Conclusion

Brexanolone, esketamine, and agomelatine illustrate three major directions in modern antidepressant development: neuroactive steroids, glutamate-based therapies, and circadian-rhythm modulation.

Brexanolone was a landmark postpartum depression treatment, although it is no longer marketed and its U.S. approval has been withdrawn. Esketamine remains an important rapid-acting option for carefully selected adults with treatment-resistant depression, but it requires supervised administration and ongoing monitoring. Agomelatine offers a distinctive melatonin-based mechanism outside the United States, accompanied by mandatory attention to liver safety.

The most appropriate antidepressant is not automatically the newest one. It is the treatment whose evidence, risks, logistics, and goals make sense for the individual patient. Anyone experiencing worsening depression, suicidal thoughts, or an inability to remain safe should seek urgent professional help. In the United States, call or text 988 for the Suicide & Crisis Lifeline, or call 911 in an immediate emergency.