Nitric Oxide Supplementation on Neurocognitive Functions in Patients With ASLD

  • End date
    Dec 31, 2023
  • participants needed
  • sponsor
    Baylor College of Medicine
Updated on 29 August 2021
nitric oxide
genetic testing
argininosuccinic aciduria


This is a study involving a dietary supplement. Patients with argininosuccinate lyase deficiency (ASLD) will be randomly assigned to receive either a nitric oxide dietary supplement or placebo for 24 weeks, and then crossed-over to receive the other treatment for 24 weeks. The investigators will assess the effects of the supplement in domains of general cognition, memory, executive functioning, and fine motor functioning in individuals with ASLD.


Argininosuccinate lyase deficiency (ASLD; also known as argininosuccinic aciduria) is the second most common urea cycle disorder (UCD) and accounts for 15-20% of all disorders of ureagenesis. Individuals with ASLD can have unique clinical and physiologic characteristics as compared to other UCDs. Previous work from the members of the UCDC have shown that in spite of having fewer episodes of hyperammonemia as compared to those with proximal blockade of the urea cycle, individuals with ASLD can develop intellectual and learning disabilities. Neurocognitive deficits have been observed even in individuals without any documented hyperammonemia. Furthermore, hepatic abnormalities including hepatomegaly, hepatic injury, fibrosis and even frank cirrhosis, and vascular issues like hypertension are well known in the disorder. Previous work from the members of the UCDC has demonstrated a tissue- and molecular-specific role for ASL in the generation of NO. ASL is not only required for the synthesis of L-arginine, the substrate for the synthesis of NO, but is also an integral member of a complex that is critical for synthesis of NO from arginine. Loss of ASL can thus lead to systemic and tissue-specific NO deficiencies, which could potentially contribute to the complex phenotype including the neurocognitive deficits. A rational therapeutic option would hence be to use a NOS-independent NO supplement.

The purpose of this study is to determine whether a dietary NO supplement, Neo-ASA, would improve general cognition, memory, executive functioning, fine motor functioning, and attention in individuals with ASLD. In this single-center trial, double-blind, randomized, placebo-controlled, crossover study, individuals with ASLD will be assigned to receive a medication containing NO dietary supplement for 24 weeks and a placebo for 24 weeks. General cognition, memory, executive functioning, and fine motor functioning will be assessed and compared at the end of treatment with placebo and Neo-ASA.

Condition Argininosuccinic Aciduria, Urea Cycle Disorder, Disorders of urea cycle metabolism
Treatment Placebo, Neo-ASA
Clinical Study IdentifierNCT03064048
SponsorBaylor College of Medicine
Last Modified on29 August 2021


Yes No Not Sure

Inclusion Criteria

Age > 6 and <50 years
Diagnosis of ASLD confirmed by biochemical OR enzymatic OR genetic testing
Has a history of compliance with diet and treatment
Negative pregnancy test and ability to use birth control method for the entire duration of the study (if the subject is of child-bearing potential)
Males who enroll in the study (and their partners) should argee to use an acceptable form of birth control for the entire duration of the study

Exclusion Criteria

Clinical or laboratory abnormality of Grade 3 or greater according to the CTCAE (or for conditions not covered by the CTCAE, a severe or life-threatening toxicity) at enrollment which, in the view of the investigator compromises safety. (Elevated plasma levels of aspartate and alanine aminotransferases, or low serum potassium will not be considered as exclusion criteria as these are phenotypic manifestations of ASLD.)
Known hypersensitivity to Neo-ASA or nitrite
Individuals currently being administered other investigational agents
Clear my responses

How to participate?

Step 1 Connect with a study center
What happens next?
  • You can expect the study team to contact you via email or phone in the next few days.
  • Sign up as volunteer to help accelerate the development of new treatments and to get notified about similar trials.

You are contacting

Investigator Avatar

Primary Contact



Additional screening procedures may be conducted by the study team before you can be confirmed eligible to participate.

Learn more

If you are confirmed eligible after full screening, you will be required to understand and sign the informed consent if you decide to enroll in the study. Once enrolled you may be asked to make scheduled visits over a period of time.

Learn more

Complete your scheduled study participation activities and then you are done. You may receive summary of study results if provided by the sponsor.

Learn more

Similar trials to consider


Browse trials for

Not finding what you're looking for?

Every year hundreds of thousands of volunteers step forward to participate in research. Sign up as a volunteer and receive email notifications when clinical trials are posted in the medical category of interest to you.

Sign up as volunteer

user name

Added by • 



Reply by • Private

Lorem ipsum dolor sit amet consectetur, adipisicing elit. Ipsa vel nobis alias. Quae eveniet velit voluptate quo doloribus maxime et dicta in sequi, corporis quod. Ea, dolor eius? Dolore, vel!

  The passcode will expire in None.

No annotations made yet

Add a private note
  • abc Select a piece of text from the left.
  • Add notes visible only to you.
  • Send it to people through a passcode protected link.
Add a private note