See the DrugPatentWatch profile for sapropterin

Sapropterin, also known as tetrahydrobiopterin, is a drug used to reduce the symptoms of phenylketonuria (PKU), a genetic disorder that can cause intellectual disability [1]. The development of sapropterin has been marked by several milestones:

1. **Discovery of Tetrahydrobiopterin**: In the 1950s and 1960s, scientists discovered tetrahydrobiopterin, the active form of biopterin, which is a cofactor for several enzymes involved in the metabolism of neurotransmitters and amino acids [2].

2. **Understanding of PKU**: In the 1960s, PKU was found to be caused by a deficiency in the enzyme phenylalanine hydroxylase, which requires tetrahydrobiopterin as a cofactor [3].

3. **Clinical Trials**: In the late 1990s and early 2000s, clinical trials were conducted to test the efficacy of sapropterin in treating PKU [4]. These trials showed that sapropterin could reduce blood phenylalanine levels in some PKU patients.

4. **FDA Approval**: In 2007, the US Food and Drug Administration (FDA) approved sapropterin for the treatment of PKU [5].

5. **Patent Expiration**: The patent for sapropterin expired in 2019, which may lead to increased accessibility and affordability of the drug [6].

Sources:

1. [Mayo Clinic. Phenylketonuria.](https://www.mayoclinic.org/diseases-conditions/phenylketonuria/symptoms-causes/syc-20353994)
2. [NIH. Tetrahydrobiopterin.](https://www.ncbi.nlm.nih.gov/books/NBK535435/)
3. [Genetics Home Reference. Phenylketonuria.](https://medlineplus.gov/genetics/condition/phenylketonuria/)
4. [ClinicalTrials.gov. Sapropterin Dihydrochloride in the Treatment of Phenylketonuria.](https://clinicaltrials.gov/ct2/show/NCT00005275)
5. [FDA. KUVAN (sapropterin dihydrochloride) Tablets.](https://www.fda.gov/drugs/postmarket-drug-safety-information-patients-and-providers/kuvan-sapropterin-dihydrochloride-tablets)
6. [DrugPatentWatch. Sapropterin.](https://www.drugpatentwatch.com/drugs/sapropterin)