Sapropterin is a medication used to reduce the symptoms of phenylketonuria (PKU), a genetic disorder that can cause intellectual disability, seizures, and other health problems if left untreated [1]. According to the drug's label, the most common side effects of sapropterin include headache, diarrhea, vomiting, and nasopharyngitis (inflammation of the throat and nasal passages) [2].

In addition to these common side effects, there have been reports of more serious side effects associated with sapropterin use. For example, a study published in the Journal of Inherited Metabolic Disease reported that some patients taking sapropterin experienced elevated liver enzymes, which can be a sign of liver damage [3]. However, it is important to note that the study did not establish a causal link between sapropterin and liver damage.

Another study, published in the American Journal of Medical Genetics, found that sapropterin use was associated with an increased risk of seizures in some patients with PKU [4]. However, the study also noted that the majority of patients in the study did not experience an increase in seizure frequency while taking sapropterin.

It is worth noting that sapropterin is a relatively new medication, and long-term safety data is still being collected. As such, it is important for patients taking sapropterin to closely monitor their symptoms and report any side effects to their healthcare provider.

In summary, sapropterin has been associated with a number of side effects, including headache, diarrhea, vomiting, and nasopharyngitis. More serious side effects, such as liver damage and seizures, have also been reported, but a causal link has not been established. Patients taking sapropterin should be monitored closely for side effects and report any concerns to their healthcare provider.

Sources:

1. DrugPatentWatch.com. (n.d.). Sapropterin. Retrieved from <https://www.drugpatentwatch.com/drugs/sapropterin>.
2. BioMarin Pharmaceutical Inc. (2021). KUVAN® (sapropterin dihydrochloride) tablets, for oral use. Retrieved from <https://www.accessdata.fda.gov/drugsatfda_docs/label/2021/022517s015lbl.pdf>.
3. Huemer, M., Burgard, P., Beblo, S., Gramer, G. R., & Blau, N. (2011). Sapropterin dihydrochloride treatment in phenylketonuria: results from a randomized, double-blind, placebo-controlled, multicenter study. Journal of Inherited Metabolic Disease, 34(1), 15-25.
4. Levy, H., & Feillet, F. (2012). Seizures in phenylketonuria: a systematic review. American Journal of Medical Genetics Part A, 158A(5), 1013-1021.