CLINICAL TRIALS PROFILE FOR GLYCINE

All Clinical Trials for glycine

Trial ID	Title	Status	Sponsor	Phase	Start Date	Summary
NCT00000371 ↗	Trial of D-Cycloserine in Schizophrenia	Completed	Massachusetts General Hospital	Phase 3	1996-08-01	To characterize further the effects of D-cycloserine augmentation of antipsychotic treatment on negative symptoms, performance on neurocognitive tasks, and on markers for glutamatergic, dopaminergic and serotonergic function in serum and cerebrospinal fluid. To determine if negative symptoms and cognitive function improve over time, if these improvements meaningfully impact quality of life factors, if they correlate with markers of neuronal function, and if subpopulations can be identified according to response. Dysfunction of glutamatergic neuronal systems has recently been implicated in the pathophysiology of schizophrenia based on the finding that non-competitive inhibitors of the NMDA receptor can reproduce in normals the positive symptoms, negative symptoms, and cognitive deficits of schizophrenia. Furthermore, glutamatergic dysfunction may alter forebrain dopaminergic neuronal activity, a system central to the antipsychotic action of typical neuroleptics. It is believed that enhancing NMDA receptor function by systemic treatment with D-cycloserine, a partial agonist at the glycine modulatory site of the NMDA receptor, will reduce symptoms in schizophrenia. Sixty schizophrenic outpatients with prominent, primary negative symptoms are treated with antipsychotic medication and are randomly assigned to D-cycloserine or placebo for a 6-month, fixed-dose trial. The primary outcome measure is the total score on the Scale for Assessment of Negative Symptoms (SANS). A neuropsychological battery, which emphasizes tests sensitive to prefrontal cortical function, is administered. Blood is obtained at several time points and CSF is obtained at Week 8 for assay of concentrations of D-cycloserine, glutamate, HVA, and 5HIAA.
NCT00000372 ↗	Glycine and D-Cycloserine in Schizophrenia	Withdrawn	Massachusetts General Hospital	Phase 3	1998-03-01	The purpose of this study is to compare the effects of D-cycloserine and glycine for treating negative symptoms (such as loss of interest, loss of energy, loss of warmth, and loss of humor) which occur between phases of positive symptoms (marked by hallucinations, delusions, and thought confusions) in schizophrenics. Clozapine is currently the most effective treatment for negative symptoms of schizophrenia. Two other drugs, D-cycloserine and glycine, are being investigated as new treatments. D-cycloserine improves negative symptoms when added to some drugs, but may worsen these symptoms when given with clozapine. Glycine also improves negative symptoms and may still be able to improve these symptoms when given with clozapine. This study gives either D-cycloserine or glycine (or an inactive placebo) with clozapine to determine which is the best combination. Patients will be assigned to 1 of 3 groups. Group 1 will receive D-cycloserine plus clozapine. Group 2 will receive glycine plus clozapine. Group 3 will receive an inactive placebo plus clozapine. Patients will receive these medications for 8 weeks. Negative symptoms of schizophrenia will be monitored through the Scale for the Assessment of Negative Symptoms, Positive symptoms will be monitored through the Positive and Negative Syndrome Scale, and additionally subjects will complete the Brief Psychiatric Rating Scale and the Global Assessment Scale. An individual may be eligible for this study if he/she is 18 to 65 years old and has been diagnosed with schizophrenia.
NCT00005658 ↗	Glycine to Treat Psychotic Disorders in Children	Completed	National Institute of Mental Health (NIMH)	Phase 2	2000-05-01	This study will test the safety and effectiveness of the amino acid glycine in treating psychotic disorders in children. The drug will be given as an adjunct (in addition) to the patient's current antipsychotic medication. Children age nine to 18 with schizophrenia or schizoaffective disorder whose symptoms began before age 13 may be eligible for this 10-week study. Patients will be hospitalized during the course of the trial. Weekend visits home may be permitted. Children enrolled in the study will be evaluated during a two-week pre-treatment period with written tests for IQ and academic functioning and with a magnetic resonance imaging (MRI) scan of the brain. For the MRI, the child lies on a table that slides into a large donut-shaped machine with a strong magnetic field. This procedure produces images of the brain that may help identify brain abnormalities in schizophrenia that develop in childhood. During the eight-week treatment phase, patients will receive glycine powder dissolved in water once a day, in addition to their other antipsychotic medications. They will undergo the following additional procedures during the course of treatment: 1. Comprehensive psychiatric examination 2. Blood pressure and pulse monitoring once a week 3. Blood tests every other week - About one ounce of blood is drawn per week to measure glycine levels 4. Eye movement study at week eight - Using a technique called infrared oculography, special detectors measure infrared light reflected off the child's eyes while he or she watches a moving square on a video monitor. 5. Lumbar puncture (spinal tap) once during the study - About one-half ounce of cerebrospinal fluid (the fluid surrounding the brain and spinal cord) is withdrawn through a needle placed in the lower part of the spine for analysis of brain chemicals. Patients who respond well may continue to receive glycine treatment through their referring physician after the study is completed. NIMH will follow patients by phone every six months and with visits at two-year intervals.
NCT00127309 ↗	Effect of Glutathione on Blood Alcohol and Hangover Symptoms	Completed	T.C Union Global Plc.	N/A	2005-06-01	Glutathione (a tripeptide of 3 amino acids - glutamic acid, cysteine and glycine) plays a great role in homeostasis, especially as a potent anti-oxidant. As an anti-oxidant, it conjugates with xenobiotics using glutathione-S-transferase (GST) and excretes in urine as mercapturic acid. In 1986, Casciani et al at the University of Milan, studied the effect of glutathione on blood alcohol, acetaldehyde and hepatic triglyceride levels and found a significant reducing effect. The blood acetaldehyde, which is the metabolic product of ethyl alcohol may have a correlation with hangover symptoms. This study is designed to find this correlation using blood alcohol, blood acetaldehyde levels and the Hangover Symptoms Scale according to the Slutske et al study.

Clinical Trial Conditions for glycine

Condition Name

Condition Name for glycine
Intervention	Trials
Schizophrenia	22
Post-Operative Pain	5
Psychoses	4
Psychotic Disorders	4

Condition MeSH

Condition MeSH for glycine
Intervention	Trials
Schizophrenia	28
Psychotic Disorders	11
Disease	10
Anemia	8

Clinical Trial Locations for glycine

Trials by Country

Trials by Country for glycine
Location	Trials
United States	84
Italy	18
China	12
Taiwan	10
Israel	9

Trials by US State

Trials by US State for glycine
Location	Trials
Maryland	11
Massachusetts	11
New York	9
California	8
Connecticut	5

Clinical Trial Progress for glycine

Clinical Trial Phase

Clinical Trial Phase for glycine
Clinical Trial Phase	Trials
PHASE1	1
Phase 4	19
Phase 3	16

Clinical Trial Status

Clinical Trial Status for glycine
Clinical Trial Phase	Trials
Completed	74
Unknown status	19
Withdrawn	11

Clinical Trial Sponsors for glycine

Sponsor Name

Sponsor Name for glycine
Sponsor	Trials
China Medical University Hospital	8
Peking Union Medical College Hospital	7
Vivozon, Inc.	6

Sponsor Type

Sponsor Type for glycine
Sponsor	Trials
Other	162
Industry	36
NIH	24

Glycine Clinical Trials Update, Market Analysis, and Revenue Projection (2026–2035)

Last updated: July 27, 2026

Glycine is an amino acid used in nutrition and supported, in specific indications, by investigational and legacy clinical evidence across rare metabolic, neurologic, and supportive-care settings. Market sizing and revenue projections depend on the specific commercial product positioning (dietary supplement vs. prescription drug vs. orphan-focused therapy) and the geographic regulatory pathway. No single, universally defined “glycine drug” exists with one FDA-approved label, one Orange Book reference set, and one late-stage pipeline, so projections must be tied to distinct development programs and route-to-market.

This brief provides a structured clinical-trials and commercialization view for “glycine” programs as a drug candidate and as a therapeutic component, with the market forecast framed by indication-level adoption and regulatory status.

Which clinical trials for glycine are active, recruiting, or recently completed?

Answer: Glycine trial activity is fragmented across (1) metabolic diseases with glycine transport or handling defects, (2) neurologic or neuroprotective hypotheses, and (3) supportive-care use cases (for example, adjunctive metabolic support). Trial counts and timelines vary widely by sponsor and study design, and many glycine studies are small, older, or not powered for registration.

What phases are glycine studies most often in?

Most glycine programs are concentrated in:

• Phase 2/2b proof-of-concept studies (biomarker-driven or functional endpoints)
• Phase 3 only for narrow, label-seeking indications
• Early-phase investigator-led or repurposing programs that test dose, tolerability, and pharmacodynamic endpoints

What endpoints does glycine research emphasize?

Common endpoint classes:

• Metabolic biomarkers tied to glycine handling and downstream metabolites
• Neurologic function or motor/speech function scores in neurologic hypotheses
• Quality of life and fatigue/functional measures in chronic supportive settings
• Plasma/CSF glycine kinetics and related safety markers (osmolarity, renal tolerance, adverse events)

How do glycine trial designs differ by therapeutic hypothesis?

• Metabolic indications: tightly controlled dosing, washout considerations, biomarker-centric analysis
• Neurologic adjuncts: endpoints often include functional scales and clinician- or patient-reported outcomes
• Supportive nutrition models: dosing regimens mirror food/pharma blend logic and safety monitoring rather than single-shot efficacy

What is the market for glycine by product type and use case?

Answer: “Glycine” commercial demand is split between bulk nutrition/industrial amino acid markets and therapeutic/clinical markets where glycine is used as a drug ingredient. Pricing power in the therapeutic segment is indication- and payer-driven, while the bulk amino acid market is volume-driven and commodity-exposed.

How does “glycine” monetization work in practice?

There are three commercially relevant lanes:

1. Dietary/nutritional products (supplements, enteral nutrition, medical nutrition)
2. Pharmaceutical-grade glycine in hospital or specialty nutrition channels
3. Prescription drug programs for rare indications or specific therapeutic constructs (where development includes regulatory labeling and payer coverage)

What drives demand growth?

• Growth in clinical nutrition volumes
• Increased use in hospital formularies when reimbursement supports it
• Orphan/rare program adoption if a label is established and stable supply is secured
• Manufacturing scale efficiency and cost reduction in high-purity grades

What risks cap the therapeutic market?

• Proof-to-label difficulty in CNS/metabolic hypotheses
• Safety and tolerability constraints at higher doses
• Competitive substitution by other amino acid strategies or specialized formulas
• Regulatory friction between “medical food,” supplement, and prescription drug classifications

How many glycine clinical programs are in the pipeline, and what is the success probability by phase?

Answer: Glycine pipeline activity is typically low-to-moderate by count but high in uncertainty. Most programs remain hypothesis-driven without the large, registrational datasets seen in mainstream small molecules.

Phase-to-success assumptions used for projection

Use phase-specific success weighting for a conservative forecast:

• Phase 1 to Phase 2: moderate technical success focus (tolerability, PK/PD)
• Phase 2 to Phase 3: high attrition (need endpoint confirmation)
• Phase 3 to approval: lower attrition but depends on endpoints and comparator adequacy

Where do approvals tend to concentrate for amino acid therapies?

• Rare diseases with biomarker-readout credibility
• Situations where standard-of-care leaves a clear unmet need
• Where glycine provides a direct mechanistic correction rather than broad symptomatic benefit

When does glycine lose exclusivity or face generic competition?

Answer: Glycine itself is a commodity amino acid in many supply channels. Generic competition is not the core exclusivity model unless a specific glycine product is protected by:

• composition-of-matter for a novel glycine formulation,
• method-of-use claims for an indication,
• delivery or prodrug constructs, or
• regulatory exclusivity tied to specific applications.

What exclusivity frameworks can apply to glycine products?

• Regulatory exclusivity for an approved NDA/BLA or orphan designation
• Patent estate limited to formulation, dosing regimen, or method-of-use
• Competing products may launch as nutrition components where drug exclusivity does not apply

What matters for “loss of exclusivity” in projections?

• Whether the product is a drug with labeled indication or a medical nutrition ingredient
• Whether there are Orange Book-listed patents for the exact NDA
• Whether payers cover it and for which diagnosis codes

What Orange Book status applies to glycine products?

Answer: There is no single, universal Orange Book listing for “glycine” as a molecule across all commercial variants. The Orange Book status is product-specific and depends on whether glycine is marketed under an NDA/BLA with listed patents for formulation, method-of-use, or manufacturing.

What you need to check conceptually for each glycine NDA

• Patent list by expiration date
• Exclusivity code in the FDA approval package
• Whether listed patents are tied to:
  • drug substance/formulation,
  • specific strength/dosage form,
  • method of administration,
  • method-of-use indication.

What patent estates protect glycine, and how strong are they for business risk?

Answer: Patent coverage, where present, is usually narrow:

• Formulation and manufacturing patents (purity specs, stability, delivery characteristics)
• Method-of-use patents for defined clinical indications
• Salt/derivative constructs only if the product uses a derivative not simply unmodified glycine

What is the business implication of narrow patent coverage?

• Lower ability to block competitors if claims are weak or easy to design around
• Higher likelihood that competition emerges via alternate formulations, dosing, or channels (medical nutrition rather than drug)

Which companies are developing glycine and competing in the same clinical space?

Answer: Glycine development is split between:

• clinical nutrition manufacturers supplying enteral or specialty formulations,
• rare disease sponsors if glycine is tested for specific metabolic/neurologic indications,
• and academic/consortium groups leading investigator-initiated studies.

Because “glycine” spans multiple therapeutic interpretations, company mapping is indication-specific rather than molecule-wide.

How does glycine compare with alternatives (other amino acids, metabolic therapies, and supportive nutrition)?

Answer: Glycine competes on:

• substitution in medical nutrition formulas,
• niche advantage if mechanistic correction improves biomarkers and reduces morbidity in rare conditions,
• and cost and tolerability versus alternative amino acids or targeted metabolic agents.

What are the key competitive differentiators?

• Purity and formulation stability
• Dose flexibility for pediatric or specific patient populations
• Evidence quality for claimed endpoints (biomarkers vs clinical outcomes)
• Access through hospital procurement and reimbursement

What market projection scenarios apply to glycine (base, bull, bear) from 2026–2035?

Answer: A defensible projection requires anchoring to an indication, regulatory pathway, and product classification. Without a single dominant FDA-labeled glycine product, projections should be scenario-based by commercialization lane.

Base case (nutrition-led adoption)

• Growth tied to clinical nutrition uptake and specialty medical nutrition penetration
• Therapeutic prescription share grows slowly unless a labeled orphan indication gains traction
• Margin compression as volume increases unless formulation IP is meaningful

Bull case (rare disease or prescription drug label)

• A clear label and payer coverage unlocks prescription adoption
• Patent/formulation protection delays direct equivalents
• Increased manufacturing scale reduces cost per dose and supports wider access

Bear case (limited translation from biomarkers)

• Clinical endpoints fail to support label expansion
• Use remains largely supportive nutrition with constrained payer reimbursement
• Competitive substitution by alternative amino acid strategies limits growth

What revenue drivers most influence glycine forecasts?

• Treatment population size in each target indication
• Dosage and duration per patient
• Net price after rebates and procurement terms
• Formulary access (hospital and payer)
• Manufacturing capacity and batch release economics
• IP and exclusivity barriers (if any) for the drug-type product

Key takeaways

• Glycine is commercially broad but clinically fragmented; the market outlook depends on whether you are forecasting commodity nutrition demand or a prescription/drug-labeled glycine program.
• Clinical trial activity is typically small and hypothesis-driven; endpoint credibility and regulatory classification are decisive for approval likelihood.
• Exclusivity and patent risk are product-specific; “glycine molecule” competition may exist through nutrition channels even when drug-like exclusivity is limited.
• Revenue projections should be scenario-based by indication and route-to-market, using payer access, net pricing, and duration-of-therapy assumptions as primary levers.

FAQs

1. Does glycine have FDA approval as a prescription drug for a specific indication?
2. Are there any Orange Book-listed patents for glycine-containing NDAs?
3. What are the most common glycine-related clinical endpoints in rare metabolic and neurologic studies?
4. How does competition work for glycine: patent-based generics versus nutrition channel substitutes?
5. What dose-limiting safety issues are most frequently monitored in glycine trials?

References

1. FDA. Orange Book: Approved Drug Products with Therapeutic Equivalence Evaluations. U.S. Food and Drug Administration.
2. ClinicalTrials.gov. Glycine studies (search results). U.S. National Library of Medicine.