Slow-Release and Extended-Release Ketamine Tablet Formulations

Slow-release and extended-release ketamine tablet formulations are designed to release the drug gradually over 6 to 12 hours instead of within the first hour, producing lower peak blood levels and requiring fewer doses per day than standard immediate-release tablets. As of August 2026, no extended-release ketamine tablet has FDA approval. The formulations available today come from specialty compounding pharmacies using matrix or coated-tablet technology, while pharmaceutical companies test proprietary versions in clinical trials for depression, chronic pain, and PTSD. This guide explains how slow-release and extended-release ketamine tablet formulations work, how their pharmacokinetics differ from immediate-release tablets, and what to ask before switching between the two.

Standard ketamine tablets are immediate-release (IR): the entire dose dissolves within minutes of reaching the stomach, producing a fast, high peak followed by a relatively short window of effect.

• Peak plasma levels (Cmax) reached within 30 to 60 minutes
• The full dose absorbs in a compressed timeframe, producing a high peak
• Blood levels decline over the following 2 to 4 hours
• Multiple daily doses are often needed to sustain effects

Extended-release (ER) tablets are engineered to release ketamine gradually, aiming for lower peak levels, therapeutic concentrations sustained over 6 to 12 hours, fewer daily doses, and a smoother onset and offset than IR tablets produce. For a closer side-by-side comparison, see our guide on immediate-release versus extended-release ketamine tablets.

Compounding pharmacies rely mainly on three delivery technologies.

• Matrix systems embed ketamine in a polymer, often hydroxypropyl methylcellulose, that swells in gastric fluid and forms a gel layer the drug diffuses through slowly. This is the most common approach for compounded ER tablets, though release can be affected by food, GI motility, and pH.
• Coated systems use enteric coatings, rate-controlling membranes, or multi-particulate pellets to control when and how fast gastric fluid reaches the drug core.
• Osmotic systems push ketamine through a laser-drilled hole in an insoluble shell at a constant rate. This produces the most consistent release profile but is typically limited to pharmaceutical manufacturing rather than compounding.

As of August 2026, no extended-release ketamine tablet has FDA approval. Compounding pharmacies can prepare ER tablets using matrix technology under USP compounding standards, but quality varies between pharmacies, and potency testing matters more for ER formulations because inconsistent matrix preparation can lead to dose dumping. Several pharmaceutical companies are also developing proprietary ER ketamine formulations in clinical trials for treatment-resistant depression, chronic pain, and PTSD, though these are not yet commercially available. For more on how manufacturing quality affects compounded tablets, see our pharmaceutical manufacturing guide, and check the FDA's Center for Drug Evaluation and Research for the current approval status of ketamine products.

The lower peak levels with ER formulations may be clinically meaningful because many of ketamine's most bothersome side effects, including dissociation, dizziness, and nausea, track with Cmax rather than total drug exposure. According to pharmacokinetic research on modified-release drug delivery, flattening the peak can allow a higher total daily dose to be tolerated with fewer peak-related side effects. Norketamine, ketamine's active metabolite, also behaves differently with ER dosing: instead of the high early peak seen after an IR dose, norketamine levels track more evenly, which may shift the therapeutic effect since norketamine has its own pharmacological activity.

Taking medication multiple times a day is a common barrier to adherence, and studies across many medication classes show once-daily dosing improves long-term consistency compared to twice- or three-times-daily regimens. See our adherence studies review for more detail. Beyond convenience, ER formulations may offer:

• Fewer peak-related side effects for patients who need to function cognitively during treatment, such as at work or with childcare
• More consistent NMDA receptor blockade for chronic pain conditions like CRPS, where the valleys between IR doses can mean periods of reduced pain control
• An option for bedtime dosing, providing overnight analgesic coverage without the intense peak that can disrupt sleep onset

Alcohol can dissolve some polymer coatings and matrix systems, which may accelerate drug release from ER tablets, another reason to avoid alcohol while taking any ketamine formulation. Switching between IR and ER tablets usually requires a dose adjustment, since the same milligram amount does not produce identical effects across the two formulations. Your provider should guide this transition and may need to titrate the new dose. GI conditions that alter transit time, including gastroparesis, short bowel syndrome, rapid transit, or a history of bariatric surgery, can make ER tablet absorption unpredictable, so discuss these conditions with your prescriber before starting an ER formulation.

If a pharmaceutical-grade ER ketamine tablet receives FDA approval for a specific indication, it could standardize dosing, open insurance coverage pathways that are currently limited for oral ketamine, and bring more clinical trial safety data than compounded versions can generate on their own. For more on current coverage gaps, see our insurance coverage guide. Until an approved product exists, compounded ER tablets remain available for patients whose providers determine they are appropriate, prepared by pharmacies with the compounding expertise to produce them reliably.