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Information for Healthcare Professionals

About PKU


Impact of Elevated Phe

Noncompliance with Diet

Nutritional Risks Associated with Diet

Cognitive Problems

Psychological Problems

Maternal PKU Syndrome

Treatment Guidelines



Many PKU Patients are Still at Risk for Psychological Problems


Psychological issues may occur in PKU patients who do not maintain low Phe levels

  • Adults with PKU who were given a Phe-restricted diet exhibited more psychiatric disorders than controls (25.7% vs 16.1%, respectively)14

Psychiatric Symptoms Are Increased in Early Managed Classic PKU Patients*†14

*Adapted from a study in which 35 PKU patients (mean age 22.2 years) were compared to a control sample of 181 subjects aged 18 years in a separate epidemiological study, based on standardized and highly structured 2-hour, face-to-face interviews with child psychologists and clinical psychiatrists.14

P<0.05 for PKU patients compared to controls.14

  • PKU patients, despite being given diet to follow, required significantly more stimulant use (26%) for attentional symptoms compared to patients in the control group (6.5%)15
    • Higher mean blood Phe levels (792 μmol/L) were associated with greater stimulant use compared to patients with lower blood Phe (486 μmol/L) (P<0.02)
Long-term studies of neurocognitive outcomes with KUVAN treatment are ongoing. Safety and long-term durability of response with KUVAN have been studied for up to 164 weeks.1


KUVAN® (sapropterin dihydrochloride) Tablets for Oral Use and Powder for Oral Solution are approved to reduce blood phenylalanine (Phe) levels in patients with hyperphenylalaninemia (HPA) due to tetrahydrobiopterin- (BH4-) responsive Phenylketonuria (PKU). KUVAN is to be used in conjunction with a Phe-restricted diet.

Important Safety Information

Treatment with KUVAN should be directed by physicians knowledgeable in the management of PKU. Prolonged exposure to elevated blood Phe levels in PKU patients can result in severe neurologic damage. Treat all patients with a Phe-restricted diet. The initiation of KUVAN therapy does not eliminate the need for careful monitoring of blood Phe levels and ongoing dietary management to ensure adequate Phe control and nutritional balance. Not all patients with PKU respond to treatment with KUVAN. Response to treatment can only be determined by a therapeutic trial of KUVAN.

KUVAN is not recommended in patients with a history of anaphylaxis to KUVAN. Hypersensitivity reactions, including anaphylaxis and rash have occurred. Discontinue KUVAN treatment in patients who experience anaphylaxis and initiate appropriate medical treatment. Continue dietary Phe restrictions in patients who experience anaphylaxis.

During clinical studies, gastritis was reported as a serious adverse reaction. Monitor patients for signs and symptoms of gastritis.

Monitor patients for hyperactivity.

KUVAN has not been studied in patients with liver or renal impairment. Patients who have these conditions should be carefully monitored when receiving KUVAN.

Monitor patients when co-administering KUVAN with medications known to inhibit folate metabolism, or with levodopa. Monitor patients for hypotension when co-administering KUVAN with medications known to affect nitric oxide-mediated vasorelaxation.

Frequent blood monitoring is recommended in the pediatric population.

Some patients receiving KUVAN can experience significant drops in blood Phe levels, and children younger than 7 years old treated with KUVAN doses of 20 mg/kg per day are at an increased risk for low levels of blood Phe compared with children 7 years and older. All patients should be monitored closely to ensure that blood Phe levels do not fall too low.

Patients should be advised to notify their physicians in cases of overdose.

The most common adverse reactions (incidence ≥4%) were headache, rhinorrhea, pharyngolaryngeal pain, diarrhea, vomiting, cough, and nasal congestion. Additional adverse reactions reported in connection with worldwide marketing include pharyngitis, esophageal pain, gastritis, dyspepsia, abdominal pain, and nausea.

To report SUSPECTED ADVERSE REACTIONS, contact BioMarin Pharmaceutical Inc. at 1-866-906-6100, or FDA at 1-800-FDA-1088 or

Please read the full Prescribing Information by clicking here.