Based on the information available, sapropterin trials have included patients with phenylketonuria (PKU), a genetic disorder characterized by a deficiency of the enzyme phenylalanine hydroxylase, which results in an accumulation of phenylalanine in the body [1]. PKU patients are typically placed on a low-protein diet, and sapropterin is used as a supplementary treatment to help control phenylalanine levels in the blood [1].

According to DrugPatentWatch.com, sapropterin has been studied in clinical trials involving both pediatric and adult PKU patients [2]. One trial included patients as young as one month old, while another trial included patients up to 65 years old [2].

In addition to PKU patients, sapropterin has also been studied in patients with certain tetrahydrobiopterin (BH4) deficiencies, which can also result in elevated phenylalanine levels [1].

It is important to note that sapropterin is not effective for all PKU patients, and its use should be determined by a healthcare professional [1].

Sources:

1. <https://www.fda.gov/drugs/postmarket-drug-safety-information-patients-and-providers/sapropterin-dihydrochloride-tablets-kuvan-information>
2. <https://www.drugpatentwatch.com/drugs/kuvan>