Two Forms That Sound Similar but Work Differently
Patients researching ketamine treatment options often encounter multiple terms for medications that dissolve in the mouth: troches, lozenges, oral dissolving tablets (ODTs), rapidly dissolving tablets (RDTs), sublingual tablets, and more. It is easy to assume these are interchangeable, but they differ in meaningful ways that affect how the medication is absorbed, how the session feels, and how the treatment works.
This article compares ketamine troches with oral dissolving tablets (ODTs), two of the most commonly discussed oral formulations. For a comparison with RDT wafers specifically, see the dedicated troche vs. RDT wafer article.
What Is a Ketamine Troche?
A troche (pronounced "TRO-key") is a compounded dosage form — a small, solid lozenge designed to dissolve slowly in the mouth. Troches are made by compounding pharmacies according to a prescriber's specifications.
Key characteristics:
- Dissolution time: 10 to 20 minutes, sometimes longer depending on the base
- Base: Typically a polyethylene glycol (PEG) base, hard candy base, or fat-based compound that dissolves gradually
- Size: Usually larger than a standard tablet — often resembling a small disc or diamond shape
- Production: Custom-compounded; formulation varies by pharmacy
- Absorption route: Primarily sublingual and buccal (through the oral mucosa), with some portion swallowed and absorbed through the GI tract
- Bioavailability: Approximately 25 to 35 percent via sublingual/buccal absorption, as detailed in the absorption mechanism article
What Is an Oral Dissolving Tablet (ODT)?
An ODT is a solid dosage form engineered to disintegrate rapidly when placed on the tongue — typically within 30 seconds to 3 minutes. ODTs are a well-established pharmaceutical technology used for many medications (ondansetron/Zofran ODT is a common example).
Key characteristics:
- Dissolution time: 30 seconds to 3 minutes (much faster than troches)
- Base: Typically a freeze-dried or compressed matrix designed for rapid disintegration (common excipients include mannitol, crospovidone, and other superdisintegrants)
- Size: Usually small, thin, and fragile
- Production: Can be manufactured commercially or compounded; ODT technology requires specific equipment
- Absorption route: Variable — some ODTs are designed for sublingual absorption, but many are designed to disintegrate and be swallowed, with absorption occurring primarily in the GI tract
- Bioavailability: Depends on the specific formulation and intended absorption route
The Critical Difference: Absorption Route
This is the most clinically important distinction between the two forms. A ketamine troche's slow dissolution is not a design flaw — it is the point. The extended time in contact with the oral mucosa allows sustained sublingual and buccal absorption, bypassing the liver's first-pass metabolism and delivering ketamine more directly into the bloodstream.
An ODT that disintegrates in <3 minutes may not allow sufficient mucosal contact time for meaningful sublingual absorption. If the medication dissolves rapidly, is mixed with saliva, and swallowed, the primary absorption route becomes gastrointestinal — which subjects ketamine to first-pass hepatic metabolism and reduces bioavailability to approximately 15 to 20 percent (compared to 25 to 35 percent via sublingual absorption from a troche).
However, some compounding pharmacies and manufacturers have developed ketamine ODT formulations specifically optimized for sublingual absorption — using technologies that release the drug onto the mucosal surface while the tablet matrix disintegrates. These are different from standard ODTs designed for swallowing.
The key question to ask about any ODT product: Is it designed for sublingual absorption, or does it disintegrate to be swallowed?
Side-by-Side Comparison
Dissolution and Session Experience
| Feature | Troche | Standard ODT |
|---|---|---|
| Dissolution time | 10-20 minutes | 0.5-3 minutes |
| Session duration | 45-90 minutes total | May be shorter due to faster dissolution |
| Taste exposure | Extended (10-20 min of bitter/flavored taste) | Brief (rapid dissolution) |
| Saliva management | Significant — must manage saliva for 10-20 min | Minimal — tablet disintegrates quickly |
| Technique required | Specific sublingual or buccal positioning | Placement on tongue; less positional technique needed |
Pharmacological Differences
| Feature | Troche | Standard ODT |
|---|---|---|
| Primary absorption route | Sublingual/buccal mucosa | Varies by formulation (GI or sublingual) |
| Bioavailability | ~25-35% | ~15-20% (GI) or ~25-35% (sublingual-optimized) |
| Onset of effects | 15-30 minutes | Variable — may be faster if sublingual, similar if GI |
| Duration of effects | 1-3 hours | Variable |
| First-pass metabolism | Partially bypassed | Fully subject to first-pass (if swallowed) or partially bypassed (if sublingual) |
Practical Considerations
| Feature | Troche | Standard ODT |
|---|---|---|
| Availability | Widely available from compounding pharmacies | Less commonly available for ketamine |
| Customization | Highly customizable (dose, flavor, base) | Less flexible; standardized formulations |
| Portability | Stable; not fragile | Often fragile; can crumble in packaging |
| Storage | Room temperature; moderate shelf life | Moisture-sensitive; some require blister packaging |
| Cost | Standard compounding fees | May be more or less expensive depending on source |
| Taste management | Extended bitter taste exposure | Briefer taste exposure |
When Might an ODT Be Preferred?
There are specific scenarios where a ketamine ODT might be chosen over a troche:
- Patients who cannot tolerate the extended taste of a dissolving troche for 10 to 20 minutes. If taste management strategies have been exhausted, a faster-dissolving form reduces taste exposure.
- Patients with difficulty managing saliva during the long dissolution period. Some patients — particularly elderly patients, those with neurological conditions affecting swallowing, or denture wearers — find the prolonged saliva management burdensome.
- Patients who need a rapid-onset rescue medication: For acute pain flares or crisis situations where faster absorption is desired, a sublingual-optimized ODT may provide quicker onset.
- Compliance considerations: A simpler administration process (place on tongue, let it dissolve in under a minute) may improve adherence for some patients.
When Is a Troche the Better Choice?
Troches remain the most commonly prescribed sublingual ketamine formulation for good reasons:
- Proven sublingual absorption: The extended dissolution time maximizes mucosal contact and sublingual bioavailability
- Wide availability: Virtually any compounding pharmacy can prepare troches; ODT formulations require specialized equipment
- Dose customization: Troches can be compounded in virtually any dose, with customized flavoring and base composition
- Established track record: The majority of published research on at-home sublingual ketamine has used troche or lozenge formulations
- Provider familiarity: Most ketamine prescribers have experience with troches and have established protocols for their use
What About the RDT Wafer?
The rapidly dissolving tablet (RDT) wafer is a specific type of ODT that has been developed specifically for sublingual ketamine delivery. It represents an attempt to combine the rapid dissolution of an ODT with the sublingual absorption advantages of a troche. For a detailed comparison, see troche vs. RDT wafer.
Questions to Ask Your Provider
If your provider or pharmacy offers a choice between a troche and an ODT formulation, consider asking:
- Is this ODT designed for sublingual absorption or for swallowing?
- What is the expected bioavailability compared to a standard troche?
- Will my dose need to be adjusted if switching between formulations?
- Does the pharmacy have experience compounding this specific formulation?
- How should the ODT be stored, and what is the shelf life?
The questions to ask your provider guide includes additional topics related to formulation selection.
The Bottom Line
Troches and ODTs are both oral dosage forms that dissolve in the mouth, but they are designed for different purposes. Troches optimize for prolonged mucosal contact and sublingual absorption. Standard ODTs optimize for rapid disintegration and ease of administration. For ketamine therapy, the absorption route matters because it directly affects how much drug reaches the bloodstream and how quickly effects are felt.
Most ketamine patients are well-served by standard compounded troches. ODTs — particularly those engineered for sublingual absorption — represent an evolving alternative that may suit specific patient needs. Discuss the options with your provider and pharmacist to determine which formulation aligns best with your treatment goals.
References
- FDA Guidance: Orally Disintegrating Tablets — FDA guidance on ODT product development and classification
- Journal of Pharmaceutical Sciences: Sublingual Drug Delivery Systems — Review of factors affecting sublingual absorption
- USP Chapter 795: Pharmaceutical Compounding — Nonsterile Preparations — Standards for compounded dosage forms including troches
- National Institute of Mental Health: Ketamine — Overview of ketamine in psychiatric treatment
- American Pharmacists Association: Compounding Resources — Professional compounding standards and guidance
Share