Sapropterin Dosage

Medically reviewed by Drugs.com. Last updated on Jun 13, 2025.

Usual Adult Dose for Phenylketonuria

Initial dose: 10 to 20 mg/kg orally once a day

• Blood phenylalanine (Phe) levels should be measured after 1 week, and then periodically; dose should be increased to 20 mg/kg/day if blood Phe levels have not decreased

Maintenance dose: Once responsiveness has been established, dose should be adjusted within the range of 5 to 20 mg/kg/day according to biochemical response.

Non-Responders:

• Patients whose phenylalanine levels do not decrease with treatment at 20 mg/kg/day for 1 month should be considered non-responders and treatment should be discontinued.

Comments:

• This drug should be used in conjunction with a phenylalanine-restricted diet.
• Existing dietary protein and Phe intake should not be modified during the evaluation period
• Response to therapy is determined by change in blood phenylalanine levels.

Use: To reduce blood phenylalanine levels in patients with hyperphenylalaninemia due to tetrahydrobiopterin- (BH4-) responsive phenylketonuria (PKU).

Usual Pediatric Dose for Phenylketonuria

1 month to 6 years:

• Initial dose: 10 mg/kg orally once a day

7 years or older:

• Initial dose: 10 to 20 mg/kg orally once a day

• Measure blood phenylalanine levels after 1 week, and then periodically; dose should be increased to 20 mg/kg/day if blood phenylalanine levels have not decreased

Maintenance dose: Once responsiveness has been established, dose should be adjusted within the range of 5 to 20 mg/kg/day according to biochemical response.

Non-Responders:

• Patients whose phenylalanine levels do not decrease with treatment at 20 mg/kg/day for 1 month should be considered non-responders and treatment should be discontinued.

Comments:

• This drug should be used in conjunction with a phenylalanine-restricted diet.
• Existing dietary protein and Phe intake should not be modified during the evaluation period
• Response to therapy is determined by change in blood phenylalanine levels.

Use: To reduce blood phenylalanine levels in patients with hyperphenylalaninemia due to tetrahydrobiopterin- (BH4-) responsive phenylketonuria (PKU).

Renal Dose Adjustments

Data not available

Liver Dose Adjustments

Data not available

Precautions

CONTRAINDICATIONS:

• None

Safety and efficacy have not been established in patients younger than 1 month.

Consult WARNINGS section for additional precautions.

Dialysis

Data not available

Other Comments

Administration advice:

• Take with a meal to increase absorption, preferably at the same time each day

Tablets:

• Swallow whole; dissolve in water or apple juice and consume; or crush tablets and mix with a small amount of soft food such as apple sauce or pudding and consume
• To dissolve: Place whole, or to speed up process, crushed tablets in 120 to 240 mL of water or apple juice; stir until dissolved (it may take a few minutes for tablets to dissolve and tablets may not completely dissolve)
• Consume tablet solution orally within 15 minutes of dissolution; if any pieces of tablet remain, add additional water or apple juice, stir, and take orally, repeat until all of the tablet is consumed

Powder for Oral Solution:

• Dissolve powder for oral solution in 120 to 240 mL of water or apple juice and take within 30 minutes of dissolution
• Powder for oral solution may also be stirred in a small amount of soft food such as apple sauce or pudding and consumed
• Patients weighing less than 10 kg: Package Labeling may be consulted for dose chart
• Dissolve oral solution in as little as 5 mL of water or apple juice and provide a portion of solution corresponding daily dose via an oral dosing syringe

Missed dose: Take as soon as possible; do not take 2 doses on the same day

Storage requirements:

• Protect from moisture

General:

• Therapy should be directed by physicians knowledgeable in the management of phenylketonuria (PKU).
• All patients should be receiving a phenylalanine-restricted diet.

Monitoring:

• Gastrointestinal: Signs of gastritis
• Metabolic: Blood Phe levels (during therapy; frequently in pediatric patients)
• Nervous system: For hyperactivity

Patient advice:

• Patients/caregivers should be instructed to read the FDA-approved patient labeling (Patient Information and Instructions for Use).
• Patients/caregivers should understand this drug must be used in conjunction with a phenylalanine-restricted diet; they should be informed of the consequences of increased or decreased phenylalanine blood concentrations.
• Patients/caregivers should understand that they will need blood tests to determine if this drug is working for them and to maintain phenylalanine levels in the desired range.
• Patients/caregivers should be instructed to notify their healthcare provider if they experience gastritis, hyperactivity, or any new symptoms.
• Patients/caregivers should be instructed to speak with their healthcare provider before starting any new medications.
• Patients who are pregnant or interested in becoming pregnant should speak with their healthcare provider.

See also:

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer