sapropterin dihydrochloride: clinical use

Prescribing considerations

• Initiate and supervise treatment through a clinician experienced in phenylketonuria and tetrahydrobiopterin deficiency.
• Establish biochemical responsiveness before continuing treatment.
• Maintain active management of dietary phenylalanine, total protein and nutritional balance.
• Use caution in older adults and in renal or hepatic impairment because evidence is limited.
• Review biochemical control during illness and adherence before altering treatment.

Contraindications and cautions

• Hypersensitivity to sapropterin dihydrochloride or any formulation excipient.

Monitoring

• Blood phenylalanine and tyrosine during response assessment and regularly thereafter.
• Nutrient and protein intake, dietary phenylalanine and overall nutritional balance.
• Growth and psychomotor or neurodevelopmental progress in children.
• Phenylalanine after treatment changes, intercurrent illness or discontinuation because low levels or rebound increases can occur.

Clinical pharmacology

Sapropterin is synthetic 6R-tetrahydrobiopterin. It enhances residual phenylalanine-hydroxylase activity in responsive phenylketonuria and replaces deficient cofactor activity in tetrahydrobiopterin deficiency; food increases its absorption.

Formulation and product differences

• Soluble tablets can be dissolved in water or apple juice, crushed into suitable soft food, or given through an appropriate enteral tube. The score line is not intended for tablet splitting.
• Powder sachets are dissolved in water. The selected powder contains potassium, which should be considered in reduced kidney function or a controlled-potassium diet.
• Prepared tablet and powder solutions have different permitted use windows; unused solution should be discarded.

Oral solution

Route: Oral

Strengths: 100 mg, 500 mg

Tablet

Route: Oral

Strengths: 100 mg