Q. A 4-day-old newborn girl is admitted to the neonatal intensive care unit due to poor feeding, lethargy, and tachypnea. Her mother had noticed increasing episodes of vomiting and decreased responsiveness since bringing her home from the hospital. Her family history is significant for a cousin who had some kind of genetic metabolic disorder. Laboratory results reveal severe hyperammonemia. The neonatologist decides to start immediate treatment to lower the newborn's serum ammonia level. Which of the following medications used in the management of hyperammonemia works by forming water-soluble products with glycine or glutamine that can be excreted through the kidneys?