Sapropterin, pharmaceutical tetrahydrobiopterin: molecular mechanisms & dependencies

How nutrients influence it

Every nutrient with a recorded effect on this component, credited to the nutrient that acted rather than the chapter that recorded it. Open a nutrient to see the findings and the conditions they were measured under.

Human evidence only

How nutrients reach it in more than one step

Chains of two or more recorded steps that end here, grouped by the nutrient they start from. Each step is a separate finding, so a chain is a route a mechanism could take, not proof that it does.

Tracing routes…

What it does

Every recorded relationship this component is part of, grouped by its role. Plain wording comes first; the technical statement follows.

Recorded relationships

What it acts on

In an 89-participant six-week PKU trial, sapropterin 10 mg/kg/day lowered mean phenylalanine by 236 micromol/L versus a 3 micromol/L rise with placebo; 44% versus 9% had at least a 30% reduction.
Sapropterin, pharmaceutical tetrahydrobiopterin → Human plasma phenylalanine concentration source_derived_draftungraded
Experimental context and source evidence
evidence_access
Primary abstract
experimental_model
Randomized human PKU study enriched through prior responsiveness assessment.
limitations
Not all PAH defects respond; trial dose is historical evidence, not individualized guidance.
nutrient_topic
L-Phenylalanine collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · L-Phenylalanine
plain_language
Providing the pharmaceutical cofactor helped some patients, with substantial response variation.
primary_references
Efficacy of sapropterin dihydrochloride (tetrahydrobiopterin, 6R-BH4) for reduction of phenylalanine concentration in patients with phenylketonuria: a phase III randomised placebo-controlled study. · 2007 · https://pubmed.ncbi.nlm.nih.gov/17693179/ · DOI 10.1016/S0140-6736(07)61234-3
L-Phenylalanine: transport, protein synthesis, cofactor recycling and cross-nutrient mechanisms (2026-09-19) · lines 222–228
AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Randomized human PKU study enriched through prior responsiveness assessment. · source_derived_draft · unverified_draft
## l-phenylalanine-sapropterin-response Providing the pharmaceutical cofactor helped some patients, with substantial response variation. In an 89-participant six-week PKU trial, sapropterin 10 mg/kg/day lowered mean phenylalanine by 236 micromol/L versus a 3 micromol/L rise with placebo; 44% versus 9% had at least a 30% reduction. Model: Randomized human PKU study enriched through prior responsiveness assessment. Limitations: Not all PAH defects respond; trial dose is historical evidence, not individualized guidance. Evidence access: Primary abstract Efficacy of sapropterin dihydrochloride (tetrahydrobiopterin, 6R-BH4) for reduction of phenylalanine concentration in patients with phenylketonuria: a phase III randomised placebo-controlled study. · 2007 · https://pubmed.ncbi.nlm.nih.gov/17693179/ · DOI 10.1016/S0140-6736(07)61234-3
Complete structured claim and evidence
In 46 preselected sapropterin-responsive children, 20 mg/kg/day allowed more supplemental dietary phenylalanine while maintaining study blood targets: 20.9 versus 2.9 mg/kg/day with placebo.
Sapropterin, pharmaceutical tetrahydrobiopterin → Dietary phenylalanine tolerance in responsive PKU children source_derived_draftungraded
Experimental context and source evidence
evidence_access
Primary abstract
experimental_model
Ten-week randomized trial after responder selection.
limitations
Selected pediatric responders cannot represent all PKU patients.
nutrient_topic
L-Phenylalanine collection; species, compartment, exposure, co-substrates and manipulation remain explicit. · L-Phenylalanine
plain_language
When processing capacity improves, a responsive patient may tolerate more dietary phenylalanine.
primary_references
Efficacy of sapropterin dihydrochloride in increasing phenylalanine tolerance in children with phenylketonuria: a phase III, randomized, double-blind, placebo-controlled study. · 2009 · https://pubmed.ncbi.nlm.nih.gov/19261295/ · DOI 10.1016/j.jpeds.2008.11.040
L-Phenylalanine: transport, protein synthesis, cofactor recycling and cross-nutrient mechanisms (2026-09-19) · lines 230–236
AI-assisted research curation; primary references, access levels and experimental limitations individually identified. Not publisher full text. · supports · Ten-week randomized trial after responder selection. · source_derived_draft · unverified_draft
## l-phenylalanine-sapropterin-tolerance When processing capacity improves, a responsive patient may tolerate more dietary phenylalanine. In 46 preselected sapropterin-responsive children, 20 mg/kg/day allowed more supplemental dietary phenylalanine while maintaining study blood targets: 20.9 versus 2.9 mg/kg/day with placebo. Model: Ten-week randomized trial after responder selection. Limitations: Selected pediatric responders cannot represent all PKU patients. Evidence access: Primary abstract Efficacy of sapropterin dihydrochloride in increasing phenylalanine tolerance in children with phenylketonuria: a phase III, randomized, double-blind, placebo-controlled study. · 2009 · https://pubmed.ncbi.nlm.nih.gov/19261295/ · DOI 10.1016/j.jpeds.2008.11.040
Complete structured claim and evidence

The events it takes part in

A mechanism often involves more than two components. These are the full events, with every participant and its role.

Situations it appears in

Low-supply and faulty-machinery situations recorded in the chapters where this component plays a part.

In the sources

Preserved passages that mention this component, quoted exactly. Open one to read it in context.

Open hypotheses

Proposed ideas that involve this component. They are labeled as hypotheses and do not change any recorded statement.

This is a research prototype built from draft material. It is not medical advice, and its statements still await verification against the original studies.

Sapropterin, pharmaceutical tetrahydrobiopterin