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Enzyme Inhibitor

Tryptophan for Schizophrenia (TrypNAC-II Trial)

Phase 1 & 2

Waitlist Available

Led By Robert W Buchanan, M.D.

Research Sponsored by University of Maryland, Baltimore

Eligibility Criteria Checklist

Specific guidelines that determine who can or cannot participate in a clinical trial

Must have

Age: 18 to 55 years

Be between 18 and 65 years old

Must not have

Monoamine oxidase inhibitors, migraine headache medications (triptans) and dextromethorphan

Active disorders that have been reported to affect tryptophan metabolism or interfere with absorption will be excluded (Acute Intermittent Porphyria, Celiac Disease, Crohn's Disease, Irritable Bowel Syndrome; Brune and Pflughaupt 1975; Torres et al 2007)

Timeline

Screening 3 weeks

Treatment Varies

Follow Up change from baseline after 3 hours on each challenge day.

Summary

This trial will give 6 grams of tryptophan to human participants to study the effects of kynurenic acid on neurotransmitters. They will use cognitive tests and magnetic resonance imaging techniques to measure brain activity and chemistry.

Who is the study for?

This trial is for adults aged 18-55 with schizophrenia, schizoaffective disorder, or schizophreniform disorder. Participants must be on a stable dose of antipsychotic medication for at least two months and agree to use contraception. Exclusions include organic brain disorders, conditions affecting tryptophan metabolism, high caffeine intake, pregnancy/lactation, metal in the body that affects MRI scans, certain medications like MAO inhibitors and substance misuse within the last three months.

What is being tested?

The study tests how N-acetylcysteine (NAC) combined with tryptophan impacts cognitive functions in people with schizophrenia-related conditions. Researchers will increase KYNA levels using tryptophan and observe changes through cognitive tests and MRIs to see how NAC influences brain activity and chemistry.

What are the potential side effects?

Potential side effects may include gastrointestinal discomfort from high doses of tryptophan or allergic reactions to NAC. Since MRIs are involved, participants might experience discomfort due to the confined space or loud noises during scanning.

Eligibility Criteria

Inclusion Criteria

You may be eligible if you check “Yes” for the criteria below

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I am between 18 and 55 years old.

Exclusion Criteria

You may be eligible for the trial if you check “No” for criteria below:

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I am not taking MAO inhibitors, triptans, or dextromethorphan.

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I do not have conditions like Celiac or Crohn's that affect nutrient absorption.

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I have a condition or have had treatment that could affect my thinking.

Timeline

Screening ~ 3 weeks3 visits

Treatment ~ Varies

Follow Up ~ the measure will be collected at baseline.

Screening ~ 3 weeks

Treatment ~ Varies

Follow Up ~the measure will be collected at baseline.

This trial's timeline: 3 weeks for screening, Varies for treatment, and the measure will be collected at baseline. for reporting.

Treatment Details

Study Objectives

Study objectives can provide a clearer picture of what you can expect from a treatment.

Primary study objectives

Kynurenic acid levels

Medial prefrontal cortex glutamate levels using magnetic resonance spectroscopy (MRS)

Medial prefrontal cortex glutathione metabolite levels using magnetic resonance spectroscopy (MRS)

+2 more

Secondary study objectives

Electrophysiological measure

Improvement in cognitive function

Peripheral Blood Mononuclear Cell (PBMC) kynurenine 3-monooxygenase (KMO) activity

+1 more

Side effects data

From 2014 Phase 3 trial • 264 Patients • NCT00650091

17%

Cough

14%

Dyspnea

13%

Upper respiratory tract infection

13%

Nausea

12%

Idiopathic Pulmonary Fibrosis

10%

Fatigue

10%

Idiopathic pulmonary fibrosis

Diarrhoea

Bronchitis

Dizziness

Nasopharyngitis

Sinusitis

Pneumonia

Headache

Atrial Fibrillation

Constipation

Acute Myocardial infarction

Oedema peripheral

Arthralgia

Intersticial Lung Disease

pneumothorax

Vomiting

Adverse Drug Reaction

Epistaxis

Dyspnoea

Lung Squamous Cell Carcinoma

Death

prostatitis

Dehydration

Prostate Cancer

syncope

Drug Fever

Exacerbation of Idiopathic Pulmonary Fibrosis

Atelectasis

Respiratory Tract Infection

100%

80%

60%

40%

20%

Study treatment Arm

Initial Study: Pred/AZA/NAC

N-Acetylcysteine

Placebo

Initial Study: Placebo

Trial Design

2Treatment groups

Experimental Treatment

Placebo Group

Group I: N-acetylcysteine & TryptophanExperimental Treatment2 Interventions

N-acetylcysteine 140 mg/kg up to a maximum of 15 g. Thirty minutes after N-acetylcysteine administration participants will receive Tryptophan, 6 grams.

Group II: Placebo & TryptophanPlacebo Group2 Interventions

Placebo 140 mg/kg up to a maximum of 15 g. Thirty minutes after placebo administration participants will receive Tryptophan, 6 grams.

Treatment

First Studied

Drug Approval Stage

How many patients have taken this drug

N-acetylcysteine (NAC)

2020

Completed Phase 3

~870

Tryptophan

2020