Purpose

The overall objective of this drug trial is to determine whether the treatment of acute hyperammonemia with N-carbamyl-L-glutamate (NCG, Carglumic acid) in propionic acidemia (PA), methylmalonic acidemia (MMA), late-onset CPS1 deficiency (CPSD) and late-onset Ornithine transcarbamylase deficiency (OTCD) accelerates the resolution of hyperammonemia efficiently and safely. The primary goal is to determine if the study drug (NCG) efficiently reduces ammonia levels following a hyperammonemia episode(s). Secondly, the investigators want to know if treatment with this study drug (NCG) efficiently improves neurologic function, reduces plasma glutamine levels and lessens the duration of hospitalization after each episode of hyperammonemia.