Short-Term Outcome of N-Carbamylglutamate in the Treatment of Acute Hyperammonemia

Inclusion Criteria

o Aged older than 1 week with an established diagnosis of CPSD or OTCD (as follows):

   - Diagnosed with late-onset CPSD confirmed by detection of pathogenic mutation(s),
   and/or decreased (<20% of control) CPS enzyme activity in liver OR

   - Diagnosed with late-onset OTCD by detection of pathogenic OTC mutation, OR decreased
   (<20% of control) OTC enzyme activity in liver OR elevated urinary orotate (greater
   than 20 µM/mM) following allopurinol loading with the absence of argininosuccinic acid

AND: Subject or subject's first-degree relative had plasma ammonia level ≥100 μmol/L >1
week of age

OR

o An established diagnosis of PA or MMA (as follows):

- Diagnosed with PA by semi-quantitative urine organic acid analysis, defined as the
presence of elevated Methylcitric acid and normal methylmalonic acid levels and no evidence
of biotin related disorders in the organic acid analysis

OR

- Diagnosed with MMA by semi-quantitative urine organic acid analysis, defined as an
elevation of methylmalonic acid and no evidence of vitamin B12 dependent disorder on plasma
amino acid analysis (B12 dependency is defined by documented B12 responsiveness)

AND: Subject or subject's first-degree relative had plasma ammonia level at any time ≥100
μmol/L

   - Able to receive medications orally, by nasogastric (NG)-tube or by gastric (G)-tube

   - No concomitant illness which would preclude safe participation as judged by the
   investigator

   - If post-menarcheal must have a negative pregnancy test prior to administration of
   study drug at each episode

   - Signed informed consent by the subject or the subject's legally acceptable
   representative

Exclusion Criteria

   - Administration of NCG within 7 days of participation in the study

   - Use of any other investigational drug, biologic, or therapy

   - Planned participation in any other clinical trial

   - Diagnosis of any medical condition causing hyperammonemia which is not PA/MMA, CPSD or
   OTCD. Other urea cycle disorders will be excluded from this study

   - Any clinical or laboratory abnormality or medical condition that, at the discretion of
   the investigator, may put the subject at additional risk by participating in this
   study

   - Has had a liver transplant

   - Is not expected to be compliant with this study in terms of returning to the site for
   subsequent episodes of hyperammonemia crises

   - Is pregnant