The Core Question: Do Troches Work as Well as Infusions?
Patients considering ketamine therapy frequently ask whether at-home troches can match the outcomes of in-clinic IV infusions. It is a reasonable question — IV infusions deliver ketamine directly into the bloodstream with 100 percent bioavailability, while sublingual troches achieve roughly 25 to 30 percent bioavailability through mucosal absorption. On a pure pharmacokinetic basis, the infusion appears to have a clear advantage.
But clinical outcomes are not determined by bioavailability alone. Dose, frequency, duration of treatment, patient selection, and the ability to sustain therapy over months all influence real-world results. The picture is more nuanced than "higher bioavailability equals better outcomes." For a detailed cost perspective, see our troches vs. IV cost breakdown.
What the IV Infusion Evidence Shows
IV ketamine for treatment-resistant depression (TRD) has the most robust evidence base of any ketamine delivery method. Key findings from major studies:
Acute Response and Remission
The landmark studies that established ketamine as a rapid-acting antidepressant used single IV infusions at 0.5 mg/kg administered over 40 minutes. In these early trials:
- Response rates (defined as 50 percent or greater reduction in depression scores) ranged from 50 to 70 percent within 24 hours of a single infusion
- Remission rates (defined as depression scores falling below a clinical threshold) were approximately 25 to 35 percent after a single infusion
- Effects were often rapid — many patients reported improvement within hours — but transient, with most relapsing within 1 to 2 weeks without additional infusions
A 2019 meta-analysis published in the American Journal of Psychiatry pooled data from multiple randomized controlled trials and found that a single IV ketamine infusion produced significantly higher remission rates compared to saline placebo in TRD, with a number needed to treat (NNT) of approximately 5 to 6 for acute response.
Serial Infusion Protocols
Most clinical practices use serial infusion protocols — typically 6 infusions over 2 to 3 weeks — rather than single infusions. Serial infusion data suggests:
- Cumulative response rates of 60 to 75 percent
- Cumulative remission rates of 25 to 40 percent
- Improved durability compared to single infusions, though maintenance infusions are still typically needed
A 2020 study in Journal of Clinical Psychiatry following patients through a series of 6 infusions found that approximately 59 percent met response criteria and 29 percent achieved remission by the end of the acute series.
Durability Concerns
The primary limitation of IV ketamine is durability. Without ongoing treatment:
- Median time to relapse after a successful infusion series is approximately 18 to 21 days
- Most patients require maintenance infusions (monthly or more frequently) to sustain benefits
- Maintenance infusion costs accumulate significantly over time
What the Troche Evidence Shows
Sublingual ketamine troches have a smaller and less rigorous evidence base. Most data comes from observational studies, retrospective chart reviews, and open-label trials rather than the randomized controlled trials (RCTs) that form the backbone of IV ketamine evidence.
Key Observational Studies
A significant retrospective study by Jamieson and colleagues (2023) examined outcomes in patients receiving at-home sublingual ketamine for depression. The study found:
- Clinically meaningful improvement in depression scores in approximately 60 percent of patients over a treatment course
- Response appeared to build over multiple doses rather than appearing rapidly after a single dose (as seen with IV)
- Patients who adhered to their prescribed regimen for at least 4 weeks showed the most consistent improvement
A 2022 study published in Journal of Affective Disorders evaluated sublingual ketamine in a clinical practice setting and reported:
- Response rates of approximately 50 to 55 percent over a treatment course of several weeks
- Lower rates of dissociative side effects compared to IV administration
- Good tolerability and low dropout rates
Dose Considerations
Sublingual troches typically range from 100 to 400 mg per session. Despite the lower bioavailability (25-30 percent transmucosal), a 200 mg troche delivers an estimated 50 to 60 mg of ketamine into systemic circulation — roughly comparable to a standard IV infusion dose for a 100 to 120 kg patient, though pharmacokinetic profiles differ. The absorption is slower, the peak concentration is lower, and the drug exposure is more prolonged compared to a 40-minute infusion.
This pharmacokinetic difference may actually matter therapeutically. Some researchers have proposed that the sustained, lower-level exposure from sublingual administration may engage different neuroplasticity mechanisms than the rapid, high-peak exposure from IV infusion. This hypothesis remains unproven but is an active area of investigation.
Why Direct Comparisons Are Difficult
As of 2025, there are no large, well-powered, randomized controlled trials directly comparing sublingual ketamine troches to IV ketamine infusions in matched populations. This evidence gap makes definitive statements about relative efficacy premature.
Several factors complicate comparison:
Different Patient Populations
IV infusion clinics tend to serve patients with severe, treatment-resistant depression who have failed multiple medication trials. Troche prescribers serve a broader population that may include patients with moderate depression, anxiety disorders, chronic pain, and other conditions. Comparing outcomes across these populations conflates the treatment effect with baseline severity differences.
Different Outcome Measures
Studies use different depression rating scales (PHQ-9, MADRS, HAM-D, BDI), different definitions of "response" and "remission," and different time points for assessment. A "response rate" in one study may not be directly comparable to a "response rate" in another.
Different Treatment Durations
IV infusion studies often measure outcomes after an acute series of 6 infusions over 2 to 3 weeks. Troche studies may assess outcomes after 4 to 12 weeks of regular home use. Comparing a 3-week intervention to a 12-week intervention requires careful consideration of what constitutes a fair comparison.
Publication and Selection Bias
IV ketamine benefits from more pharmaceutical and academic research investment. Sublingual troche data comes more frequently from clinical practice settings, where research methodology may be less rigorous and publication bias can affect what gets reported.
What We Can Reasonably Conclude
Despite the limitations of cross-study comparison, several patterns emerge:
IV Infusions Likely Produce Faster Acute Response
The pharmacokinetics of IV administration — rapid onset, high peak plasma levels — appear to produce more dramatic acute responses, particularly in the first 24 to 72 hours. Patients in crisis or with acute suicidality may benefit more from the speed of IV response.
Troches May Be Comparable for Sustained Outcomes
When treatment adherence is maintained over weeks to months, troche outcomes appear to approach IV outcomes for many patients. The ability to dose regularly at home — rather than traveling to a clinic for periodic infusions — supports a more consistent therapeutic exposure pattern.
Troches Have Practical Advantages for Long-Term Use
The economics and logistics of ketamine therapy heavily favor troches for maintenance treatment:
- Cost: Troches typically cost $50 to $200 per month. Maintenance IV infusions cost $400 to $800 per session.
- Frequency: Regular home dosing (2 to 3 times per week) is logistically simpler than clinic visits
- Consistency: More frequent, lower-dose exposures may produce more stable mood effects than periodic high-dose infusions
Some Patients May Benefit from a Sequential Approach
A growing clinical pattern involves starting with IV infusions for rapid acute response, then transitioning to at-home troches for maintenance. This approach combines the acute efficacy advantages of IV with the practical sustainability of troches. Some providers refer to this as a "step-down" or "bridge" protocol.
Chronic Pain Outcomes
For chronic pain conditions — an indication where ketamine is also used off-label — the comparison landscape is even less clear. IV ketamine infusions for chronic pain typically use higher doses (0.5 to 1.0 mg/kg/hour for multi-hour infusions) than those used for depression. Published pain outcomes with troches tend to come from case series and clinical reports rather than controlled trials.
Early observational data suggests that troches can provide meaningful pain reduction for some chronic pain patients, particularly those with neuropathic pain conditions. However, the magnitude of pain relief may be lower than that achieved with high-dose IV protocols. This remains an active area of clinical investigation.
Questions to Ask Your Provider
If you are deciding between troches and IV infusions, these questions can help guide the conversation:
- Based on my diagnosis and severity, which route do you recommend starting with?
- What outcomes have you observed in patients similar to me with each method?
- If I start with one method, can I switch to the other if results are insufficient?
- What does the maintenance phase look like with each approach, including cost and logistics?
- Are there specific reasons — medical, psychiatric, or practical — that make one approach clearly better for me?
The Evolving Evidence Landscape
Research into sublingual ketamine is accelerating. Several clinical trials are underway or recently completed that will provide more rigorous data on troche outcomes, including some that include IV comparator arms. As this evidence matures over the next few years, the relative positioning of troches and infusions in treatment algorithms will become clearer.
For now, the honest summary is this: IV infusions have stronger evidence for rapid, acute antidepressant response. Troches have growing evidence for meaningful clinical benefit with substantial advantages in cost, convenience, and sustainability. The "best" option depends on clinical severity, treatment goals, practical circumstances, and individual response — which is why the decision should be made collaboratively with a knowledgeable prescriber.
References
- Efficacy of IV Ketamine for Treatment-Resistant Depression: A Systematic Review and Meta-Analysis — Comprehensive meta-analysis of randomized controlled trials of IV ketamine in TRD
- Single vs. Repeated Ketamine Infusions for Depression — Evidence on serial infusion protocols and cumulative response rates
- Sublingual Ketamine for Depression: Observational Data — Clinical practice outcomes with sublingual ketamine formulations
- Pharmacokinetics of Sublingual vs. Intravenous Ketamine — Comparative pharmacokinetic data across administration routes
- NIMH: Rapid-Acting Antidepressant Research — NIH overview of ketamine and rapid-acting antidepressant development
- Durability of Ketamine Antidepressant Effects — Evidence on relapse timelines following ketamine treatment
- Cost-Effectiveness of Ketamine Treatment Modalities — Economic analysis comparing different ketamine delivery approaches
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