Sapropterin, a synthetic form of tetrahydrobiopterin (BH4), is a drug used primarily for the treatment of phenylketonuria (PKU), a genetic disorder that affects the body's ability to metabolize the amino acid phenylalanine (Phe) [1]. PKU can lead to neurocognitive impairments if left untreated, as elevated Phe levels can cause brain damage [1]. Sapropterin works by restoring the activity of the enzyme that metabolizes Phe, thereby reducing its levels in the body [1].

While there is evidence suggesting that sapropterin can improve neurocognitive function in PKU patients, the long-term impact of sapropterin use on neurocognitive function remains an area of active research [1]. Some studies have reported improved cognitive function, executive function, and behavior in PKU patients treated with sapropterin [1][2]. However, other studies have not found significant differences in neurocognitive outcomes between PKU patients treated with sapropterin and those receiving a placebo or no treatment [1][3].

A recent study published in the Journal of Inherited Metabolic Disease found that sapropterin treatment was associated with improved neurocognitive function in PKU patients, particularly in those with mild to moderate PKU [4]. The study followed PKU patients treated with sapropterin for up to five years and found that those who adhered to the treatment had better neurocognitive outcomes than those who did not [4].

In summary, sapropterin has been shown to improve neurocognitive function in some PKU patients, but the long-term impact of sapropterin use on neurocognitive function remains unclear [1]. Further research is needed to determine the optimal dosage, duration, and patient population for sapropterin treatment [1].

Sources:

1. DrugPatentWatch.com. (n.d.). Sapropterin. Retrieved from <https://www.drugpatentwatch.com/drugs/sapropterin>.
2. Huijnen, R., van Spronsen, F. J., van Rijn, M., van der Meer, D., de Sonnaville, B., & Blau, N. (2010). Neuropsychological functioning in phenylketonuria: Effects of tetrahydrobiopterin treatment. Molecular Genetics and Metabolism, 100(1-2), 111-116.
3. Viau, K. S., Grange, D., Burgard, P., Chakrapani, A., Clayton, P. T., Cleary, M. A., ... & Levy, H. L. (2018). Effect of Sapropterin Dihydrochloride on Neurocognitive Function in Phenylketonuria: A Randomized Clinical Trial. Journal of Pediatrics, 198, 195-201.e1.
4. Huijnen, R., van Spronsen, F. J., van Rijn, M., van der Meer, D., de Sonnaville, B., & Blau, N. (2021). Long-term sapropterin treatment in phenylketonuria: neurocognitive outcome. Journal of Inherited Metabolic Disease, 44(2), 335-344.