Introduction
Sublingual and oral ketamine formulations have become increasingly utilized in outpatient psychiatric practice, particularly within telehealth-integrated treatment models. Unlike IV ketamine and intranasal esketamine (Spravato), oral and sublingual preparations are prescribed off-label and are not subject to a formal REMS program, though they carry significant clinical responsibilities regarding patient selection, dosing, and safety monitoring. These formulations are typically compounded as sublingual troches (also called lozenges or rapidly dissolving tablets), oral capsules, or oral liquid solutions. This document reviews the standard clinical approach to prescribing and managing sublingual and oral ketamine protocols.
Pharmacokinetic Considerations
Bioavailability Differences
The route of administration significantly influences ketamine's pharmacokinetic profile. IV administration achieves 100% bioavailability, while sublingual absorption yields approximately 25-35% bioavailability when the medication is held in the oral mucosa for the recommended duration. Oral (swallowed) ketamine has the lowest bioavailability at approximately 16-24%, owing to extensive first-pass hepatic metabolism. However, oral administration produces higher concentrations of norketamine, an active metabolite that may contribute to sustained antidepressant effects through its own NMDA receptor activity. For a detailed discussion of bioavailability optimization, see the guide on oral bioavailability.
Sublingual Administration Technique
Proper sublingual technique is essential for maximizing bioavailability. Patients are instructed to place the troche under the tongue or between the cheek and gum and allow it to dissolve slowly over 10-15 minutes without chewing or swallowing. Saliva saturated with dissolved ketamine should be retained in the mouth as long as tolerable, ideally for the full dissolution period, before expectorating or swallowing the remaining liquid. Swallowing prematurely diverts the medication to oral absorption, reducing effective plasma concentrations.
Dosing Protocols
Initial Dosing and Titration
Sublingual ketamine troches for depression are commonly initiated at doses ranging from 50 to 100 mg per session. Conservative prescribers may begin at 50 mg and titrate upward in 50 mg increments based on response and tolerability. Typical therapeutic doses range from 100 to 300 mg sublingually, though some patients may require doses up to 400 mg to achieve adequate response. The wide dosing range reflects individual variability in mucosal absorption, body composition, and metabolic enzyme activity.
Oral ketamine capsules, when used, are typically dosed at 0.5 to 1.5 mg/kg, acknowledging the lower bioavailability of the swallowed route. Some clinicians prefer the oral route for patients who experience excessive dissociation with sublingual administration, as the lower peak plasma concentrations may produce a more gradual and tolerable psychoactive experience.
Session Frequency
During the induction phase, at-home sublingual ketamine is commonly prescribed two to three times per week for the first two to four weeks. Patients who demonstrate meaningful clinical improvement then transition to a maintenance schedule of once weekly to once every two weeks, with further spacing based on the durability of symptom relief. Treatment duration is individualized, though periodic reassessment at intervals of no longer than three months is advisable.
At-Home Treatment Framework
Patient Selection
Not all patients are appropriate candidates for unsupervised at-home ketamine administration. Suitable candidates should demonstrate psychiatric stability sufficient to follow dosing instructions reliably, have no active substance use disorder (particularly involving ketamine, PCP, or other dissociatives), possess a stable and safe home environment, and have a designated treatment monitor present during sessions. Patients with a history of psychosis, poorly controlled hypertension, or significant cognitive impairment are generally excluded from at-home protocols.
Treatment Monitor Role
A treatment monitor is a sober, responsible adult who remains present throughout the dosing session and for at least two hours following administration. This individual is briefed on potential side effects, instructed not to leave the patient unattended, and provided with emergency contact information for the prescribing clinic. The monitor should be prepared to contact emergency services if the patient experiences severe hypertension, respiratory distress, prolonged unresponsiveness, or a psychiatric emergency.
Environmental Safety Measures
Patients should be instructed to prepare their treatment environment in advance. This includes securing a comfortable reclining position, removing tripping hazards from the immediate area, placing a phone within reach, and ensuring the home is locked. Driving, cooking, caring for children, and operating any machinery are strictly prohibited during and for several hours after treatment. Many clinicians recommend that patients fast for at least two hours before dosing to reduce nausea risk.
Telehealth Integration and Monitoring
Virtual Check-Ins
Telehealth platforms have become central to at-home ketamine treatment models. Initial psychiatric evaluations, informed consent discussions, and follow-up assessments are commonly conducted via secure video visits. Many programs require a brief virtual check-in before each dosing session to confirm clinical stability, review vital signs (patients may be asked to use a home blood pressure cuff), and assess for any changes in medications or clinical status that might warrant holding the dose.
Outcome Tracking
Standardized self-report instruments, including the PHQ-9 and the GAD-7, should be administered at regular intervals, ideally at each follow-up visit. Tracking treatment response over time enables clinicians to make evidence-informed decisions about dose adjustments, frequency changes, or treatment discontinuation. Some practices integrate digital platforms that prompt patients to complete these assessments electronically between visits.
Safety Considerations and Risk Mitigation
Diversion and Misuse Prevention
Because compounded ketamine is dispensed directly to patients, diversion and misuse represent meaningful clinical concerns. Best practices include prescribing limited quantities per refill (sufficient for one to two weeks of treatment), requiring regular follow-up visits as a condition of continued prescribing, monitoring for dose escalation requests or early refill patterns, and maintaining transparent documentation of clinical rationale. Urine drug screening may be incorporated at the prescriber's discretion.
Adverse Effects and When to Seek Care
Patients should receive written instructions outlining expected side effects, including mild dissociation, drowsiness, dizziness, and nausea, as well as warning signs requiring immediate medical attention. These include chest pain, severe headache, persistent vomiting, confusion lasting beyond two hours, or any urinary symptoms such as pain, blood in urine, or significant frequency changes. Clinicians should proactively screen for lower urinary tract symptoms at each follow-up, as ketamine-associated cystitis, though more commonly reported with recreational abuse, has been observed in clinical populations receiving repeated therapeutic doses. For a broader review, see long-term safety considerations.
Informed Consent
Given the off-label nature of sublingual and oral ketamine prescribing, thorough informed consent is essential. Documentation should clearly state that these formulations are not FDA-approved for depression, outline known risks and benefits, describe the limitations of the existing evidence base for long-term safety, and establish the patient's agreement to comply with treatment monitoring protocols, including the presence of a treatment monitor during sessions.
References
- DailyMed: FDA Drug Label Information — National Library of Medicine database for official drug labeling relevant to compounded ketamine formulations
- MedlinePlus: Ketamine Injection Drug Information — National Library of Medicine patient medication information for ketamine
- PubMed: Ketamine: A Review of Clinical Pharmacokinetics and Pharmacodynamics — Comprehensive pharmacokinetic review including oral bioavailability and sublingual absorption data
- FDA MedWatch: Safety Information and Adverse Event Reporting — FDA safety monitoring resource for reporting adverse events with off-label ketamine use
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