Identifying the Treatment-Resistant Depression Candidate
Patients who fail standard antidepressant care are screened for rapid-acting options.
- ~30%: Treatment-resistant depression (of MDD patients, roughly)
- ≥2: Prior failed antidepressant trials (required for TRD label)
- 2019: Esketamine FDA approval (for TRD, with an oral AD)
- Since 1990s: IV ketamine off-label use (anesthetic repurposed for mood)
Screening criteria and referral pathway
Multiple failed trials and symptom severity guide referral timing.
Why speed of onset matters clinically
Suicidality and functional decline make faster relief a priority.
Placeholder: rapid-onset framing matters most for high-risk patients.
Esketamine Spray or IV Ketamine in a Monitored Setting
Dosing happens under direct clinical observation for safety.
- 56/84 mg: Esketamine dose range (intranasal, twice weekly start)
- 0.5 mg/kg: IV ketamine dose (over ~40 minute infusion)
- ≥2 hours: Post-dose monitoring (blood pressure, dissociation checks)
- Intranasal / IV: Administration route (clinic-only, no take-home)
Why in-clinic supervision is required
Transient dissociation and blood pressure changes need monitoring.
Induction versus maintenance dosing phase
Induction is frequent; maintenance dosing spaces out over time.
NMDA Receptor Blockade Triggers an Immediate Glutamate Surge
Receptor-level pharmacology unfolds within minutes of dosing.
- Minutes: NMDA blockade onset (receptor engagement is fast)
- NMDA receptor: Primary molecular target (on GABAergic interneurons)
- Within session: Downstream glutamate surge (disinhibition-driven release)
- NMDA antagonist: Drug mechanism class (distinct from monoamine drugs)
Receptor pharmacology within the treatment session
Blockade of NMDA receptors happens essentially in real time.
Why this differs from monoamine reuptake drugs
Direct receptor action skips the slow adaptation classical drugs need.
Placeholder: fast receptor event, not gradual monoamine adaptation.
Symptom Relief Within Hours Instead of Weeks
Measurable mood improvement appears far faster than SSRIs.
- 2–24 hrs: Ketamine antidepressant onset (often same-day report)
- 4–6 wks: Classical SSRI/SNRI onset (typical clinical latency)
- ~50–70%: TRD response rate (with ketamine/esketamine, roughly)
- ~20–40x faster: Relative speed advantage (illustrative onset comparison)
The hours-versus-weeks contrast in practice
Patients often report change before the next clinic visit.
Clinical significance of same-day response
Rapid relief is critical when suicidality demands urgent action.
Rapid but Shorter-Lived vs. Slow but Sustained
Two curves, two trade-offs — speed against durability.
- ~1–2 wks/dose: Ketamine effect duration (without maintenance dosing)
- Weekly → biweekly: Typical maintenance schedule (taper after induction phase)
- Sustained daily: Classical antidepressant duration (while medication continues)
- Common: Relapse risk without upkeep (for both tracks, differently)
Why ketamine needs repeat maintenance dosing
Benefit fades over days to weeks without booster sessions.
Why classical antidepressants sustain differently
Continuous daily dosing maintains a steadier, slower-built effect.
Placeholder: choose track based on urgency versus durability needs.