Same Family, Different Members
If you have been researching ketamine therapy, you have probably encountered two closely related terms: ketamine and esketamine. They sound almost identical, and for good reason — they are chemically related. But the differences between them matter when it comes to your treatment options, insurance coverage, and clinical experience.
This guide explains the relationship between these two molecules in plain terms, so you can understand your options and have an informed conversation with your provider.
The Chemistry (Made Simple)
Ketamine exists as a molecule that has two mirror-image forms — like your left and right hands. These mirror forms are called enantiomers. The two enantiomers of ketamine are:
- S-ketamine (esketamine) — the "left hand"
- R-ketamine — the "right hand"
When you hear "ketamine" without further specification, it usually refers to racemic ketamine — the naturally occurring mixture that contains equal parts of both the S and R enantiomers. This is the form that has been used in medicine since 1970.
Esketamine is just the S-enantiomer isolated on its own. It was developed into a branded medication called Spravato by Janssen Pharmaceuticals and delivered as a nasal spray.
How They Work in the Brain
Both ketamine and esketamine work primarily by modulating NMDA receptors in the glutamate system, which promotes neuroplasticity and has rapid antidepressant effects. However, there are nuanced differences:
Esketamine (S-Ketamine)
- Has approximately three to four times stronger binding affinity at the NMDA receptor compared to R-ketamine
- Produces more pronounced dissociative effects at a given dose
- Is metabolized more quickly in the body
- Its stronger NMDA binding may allow for lower effective doses
R-Ketamine
- Has weaker NMDA receptor binding
- Produces less dissociation at equivalent doses
- Some research suggests it may have distinct antidepressant properties, potentially through non-NMDA mechanisms (such as AMPA receptor activation)
- Is being studied as a potential standalone treatment, though no R-ketamine-specific drug is currently approved
Racemic Ketamine (Both Together)
- Contains both enantiomers, providing a combination of their effects
- Has the longest clinical track record
- The interplay between S and R enantiomers may offer complementary therapeutic benefits that neither provides alone
- Some researchers believe the racemic mixture is therapeutically superior, though this remains debated
FDA Status
This is one of the most practically important differences:
Esketamine (Spravato)
- FDA-approved for treatment-resistant depression (2019) and major depressive disorder with suicidal ideation (2020)
- Available only as a nasal spray (Spravato) administered in certified healthcare facilities
- Must be used alongside an oral antidepressant per FDA guidelines
- Has a specific REMS (Risk Evaluation and Mitigation Strategy) program governing its use
Racemic Ketamine
- FDA-approved as an anesthetic (since 1970), but NOT specifically approved for depression, anxiety, or other psychiatric conditions
- Used off-label for psychiatric conditions based on clinical evidence
- Available in multiple forms: IV infusion, intramuscular injection, sublingual tablets/troches, oral formulations
- No REMS restrictions — can be prescribed by any qualified provider
The FDA approval of esketamine has significant practical implications, particularly for insurance coverage. Because Spravato has a specific psychiatric indication, insurance companies are far more likely to cover it than generic racemic ketamine used off-label.
How They Are Administered
Esketamine (Spravato)
- Nasal spray only
- Self-administered under supervision at a certified facility
- Mandatory two-hour monitoring period after each session
- Cannot be taken home
- Fixed dose strengths (56 mg and 84 mg)
Racemic Ketamine
- Available through multiple routes:
- IV infusion — Most common clinical route; highest bioavailability (nearly 100%)
- Intramuscular injection — Quick onset, slightly lower bioavailability
- Sublingual/oral — Can be done at home; lowest bioavailability (25-35%)
- Compounded nasal spray — Some compounding pharmacies prepare racemic ketamine nasal sprays, though these are distinct from Spravato
- Greater flexibility in dosing and administration
- Can be prescribed for at-home use (sublingual form)
Effectiveness: How Do They Compare?
This is the question patients most want answered, and the honest answer is: both are effective, and direct head-to-head data is limited.
What the Evidence Shows
- Esketamine (Spravato) has robust clinical trial data from the studies that led to its FDA approval. These trials demonstrated statistically significant improvement in treatment-resistant depression compared to placebo.
- Racemic IV ketamine has a larger total body of research, with studies dating back to the early 2000s showing rapid antidepressant effects. Response rates in clinical studies are generally reported as 60-70 percent for treatment-resistant depression.
- Limited head-to-head comparisons exist. Some studies suggest that racemic IV ketamine may produce response rates that are at least as high as — and possibly higher than — intranasal esketamine. However, these comparisons are complicated by differences in bioavailability, dosing, and study design.
The Clinical Perspective
Many clinicians who have experience with both believe that IV racemic ketamine is at least as effective as, if not more effective than, Spravato for most patients. However, Spravato's FDA approval, standardized protocol, and insurance coverage make it the more practical choice for many patients.
Cost and Insurance
Esketamine (Spravato)
- $600-$900 per session without insurance
- Often covered by insurance for patients with treatment-resistant depression
- Copays with insurance typically $0-$200
- Manufacturer savings program available for eligible patients
- Over the course of treatment, insured patients may pay significantly less than they would for generic ketamine
Racemic Ketamine
- IV infusion: $400-$800 per session, rarely covered by insurance
- Sublingual (telehealth): $150-$450/month, rarely covered by insurance
- The lack of insurance coverage for off-label use is the biggest financial disadvantage
- Self-pay is the norm for most racemic ketamine patients
The Experience
Esketamine Sessions
The dissociative experience with Spravato is moderate — most patients describe it as manageable and somewhat dreamlike. The nasal route delivers medication more slowly than IV, resulting in a more gradual onset. Sessions take about 2.5-3 hours total including the monitoring period.
Racemic Ketamine IV Sessions
The IV route produces a more rapid onset and typically a more intense dissociative experience than Spravato. Some patients prefer this intensity; others find it more challenging. Total clinic time is about 1.5-2.5 hours.
Racemic Ketamine Sublingual
The mildest experience of the three. The lower bioavailability results in a gentler, more gradual onset and a less pronounced dissociative state. This route offers the most convenience but the least clinical intensity.
Side-by-Side Summary
| Feature | Esketamine (Spravato) | Racemic Ketamine |
|---|---|---|
| FDA approval for depression | Yes | No (off-label use) |
| Insurance coverage | Often covered | Rarely covered |
| Routes available | Nasal spray only | IV, IM, sublingual, oral |
| Bioavailability (nasal) | ~45-50% | IV: ~100%; sublingual: ~25-35% |
| At-home option | No | Yes (sublingual) |
| Dissociative intensity | Moderate | Varies by route (mild to strong) |
| Research volume | FDA trial data | Larger total evidence base |
| Cost without insurance | $600-$900/session | $150-$800 depending on route |
| Monitoring requirement | 2 hours (FDA mandated) | Varies by provider |
Which Is Right for You?
The choice between esketamine and racemic ketamine often comes down to practical considerations:
Esketamine (Spravato) may be the better choice if:
- Your insurance covers it (this can be the deciding factor)
- You have been diagnosed with treatment-resistant depression
- You want the reassurance of an FDA-approved treatment
- You prefer a standardized, regulated protocol
Racemic IV ketamine may be the better choice if:
- You want the strongest evidence and highest bioavailability
- You are willing to pay out of pocket
- Your provider recommends it based on your clinical profile
- You are comfortable with a potentially more intense experience
Racemic sublingual ketamine may be the better choice if:
- Affordability is your top priority
- You prefer at-home treatment
- You want a gentler experience
- You are using it for maintenance after an initial IV series
The Bottom Line
Ketamine and esketamine are close relatives — both effective, both safe when properly administered, and both capable of providing meaningful relief for people struggling with depression and other conditions. The "best" choice between them is the one that fits your clinical needs, financial situation, and personal preferences.
Discuss both options with your provider, ask about their experience with each, and make the decision together. For more detail, see our in-depth comparison of Spravato vs generic ketamine. Either path can be a powerful step toward feeling better.
References
- NIMH: Cracking the Ketamine Code — NIMH feature on the research behind both ketamine and esketamine as depression treatments
- Mayo Clinic: Treatment-Resistant Depression — Mayo Clinic overview of treatment-resistant depression options including esketamine
- MedlinePlus: Ketamine Injection — National Library of Medicine drug information on racemic ketamine