Question

Kuvanis an FDA-approved medication for treating PKU patients, and is a synthetic version of BH4. The makers of Kuvan assert that “Treatment with BH4 can activate residual PAH enzyme to improve metabolism of Phe and decrease blood Phe levels in patients who respond”. This statement is not entirely accurate. Explain.

Answer 1

• Kuvan (sapropterin hydrochloride) was approved by the U.S. Food and Drug Administration (FDA) to treat PKU. Kuvan reduces blood Phe levels in patients with hyperphenylalaninemia (HPA) due to tetrahydrobiopterin (BH4-) responsive PKU.
  • Kuvan is a pharmaceutical formulation of BH4, the natural cofactor for the PAH enzyme, which stimulates activity of the residual PAH enzyme to metabolize Phe into tyrosine and decreases blood Phe levels in patient with hyperphenylalaninemia(HPA)due to BH4 responsive PKU.
• Kuvan is to be used in conjunction with a Phe-restricted diet.