sapropterin dihydrochloride at a glance
Medicine class
Synthetic tetrahydrobiopterin cofactor used in inherited metabolic disorders.
Who may benefit
Only people shown to respond through blood phenylalanine monitoring.
Diet
Specialist dietary management and monitoring must continue during treatment.
Administration
Taken with a meal; soluble tablets and powder are prepared before swallowing.
What is sapropterin dihydrochloride used for?
Uses in people shown to respond to sapropterin are:
Hyperphenylalaninaemia associated with phenylketonuria.
Hyperphenylalaninaemia associated with tetrahydrobiopterin deficiency.
How does sapropterin dihydrochloride work?
Tetrahydrobiopterin helps phenylalanine hydroxylase convert phenylalanine into tyrosine. Sapropterin supplies this cofactor: in responsive phenylketonuria it improves residual enzyme activity, while in tetrahydrobiopterin deficiency it replaces deficient cofactor activity.
sapropterin dihydrochloride preparations and strengths
Oral solution
Route: Oral
Strengths: 100 mg, 500 mg
Tablet
Route: Oral
Strengths: 100 mg
How to take sapropterin dihydrochloride
Follow the metabolic team's preparation instructions and take sapropterin with a meal to improve absorption. Do not independently alter the prescribed phenylalanine-restricted diet.
Dissolve soluble tablets in water or apple juice; they may also be crushed into a small amount of suitable soft food. Use the preparation within 15–20 minutes.
Dissolve oral powder in the instructed amount of water and use it within 30 minutes; discard any remainder.
Small visible particles in a tablet solution do not reduce its effectiveness.
For young children or partial prepared volumes, use the measuring cup and oral syringe provided or recommended by the specialist centre.
Dissolved soluble tablets may be administered through a suitable enteral feeding tube under healthcare-professional guidance.
sapropterin dihydrochloride side effects
Common or expected effects
- Headache
- Runny nose, nasal congestion, sore throat or cough
- Nausea, vomiting, abdominal pain, indigestion or diarrhoea
- Phenylalanine levels becoming too low on blood testing
Get urgent medical advice
- Serious allergic reaction, including hives, breathing difficulty, severe dizziness or swelling of the tongue or throat
- New or worsening seizures, particularly during concurrent levodopa treatment
sapropterin dihydrochloride in pregnancy
Strict control of phenylalanine before and throughout pregnancy is important because uncontrolled maternal PKU can seriously harm fetal development. Specialist-supervised dietary management is central; sapropterin may be considered for a known responder when diet alone does not provide adequate control. Discuss pregnancy plans or a confirmed pregnancy promptly with the metabolic and maternity teams.
sapropterin dihydrochloride while breastfeeding
The selected product information advises against use while breastfeeding because it is unknown whether sapropterin or its metabolites enter human milk. Discuss feeding and treatment options with the metabolic team rather than stopping treatment without advice.
sapropterin dihydrochloride interactions
Tell the prescriber about all medicines, including topical treatments. Important interactions include:
Methotrexate, trimethoprim and other dihydrofolate-reductase inhibitors
These may interfere with tetrahydrobiopterin metabolism and could affect the response to sapropterin.
Nitrates, phosphodiesterase-5 inhibitors, minoxidil and other vasodilators
Concurrent use requires clinical review and caution.
Common questions about sapropterin dihydrochloride
Answers are fully visible for fast scanning and source review.
Why does sapropterin dihydrochloride work only for some people with phenylketonuria?
It needs enough remaining phenylalanine-hydroxylase activity to improve. Responsiveness is confirmed by monitoring the change in blood phenylalanine.
Does sapropterin dihydrochloride replace the phenylalanine-restricted diet?
No. Dietary phenylalanine and overall protein intake still need specialist management, although some responders may tolerate more dietary phenylalanine.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.