Home Drug Guide Sapropterin Dihydrochloride

Drug Guide

Generic Name

Sapropterin Dihydrochloride

Brand Names Kuvan, Zelvysia

Classification

Therapeutic: Dietary supplement and enzyme activator for PKU

Pharmacological: Tetrahydrobiopterin (BH4) analog that acts as a cofactor for phenylalanine hydroxylase

FDA Approved Indications

Phenylketonuria (PKU) in pediatric and adult patients with BH4-responsive phenylalanine hydroxylase deficiency

Mechanism of Action

Sapropterin acts as a synthetic form of tetrahydrobiopterin (BH4), a natural cofactor for phenylalanine hydroxylase, increasing enzyme activity and thus reducing blood phenylalanine levels in responsive individuals.

Dosage and Administration

Adult: Initial dose typically 10 mg/kg/day divided in three doses; titrate based on response.

Pediatric: Dose varies; typically 10 mg/kg/day divided in three doses, adjusted based on phenylalanine levels.

Geriatric: No specific adjustments; consider renal and hepatic function.

Renal Impairment: Use with caution; no specific dosage adjustments available.

Hepatic Impairment: Use with caution; no specific adjustments available.

Pharmacokinetics

Absorption: Rapid absorption after oral administration.

Distribution: Widely distributed in body tissues.

Metabolism: Metabolized mainly by hepatic pathways.

Excretion: Excreted primarily in urine.

Half Life: Approximately 3-4 hours.

Contraindications

Known hypersensitivity to sapropterin or any component of the formulation.

Precautions

Monitor blood phenylalanine levels regularly; risk of hypophenylalaninemia.
Use with caution in patients with renal or hepatic impairment.
Pregnancy category C; benefits must outweigh risks during pregnancy.
Lactation: no data available - use with caution.

Adverse Reactions - Common

Headache (Common)
Diarrhea (Common)
Vomiting (Common)

Adverse Reactions - Serious

Anaphylaxis (Rare)
Hypophenylalaninemia leading to neurological symptoms (Rare)

Drug-Drug Interactions

Levodopa (may require dose adjustment).
Antihypertensive agents (monitor blood pressure).

Drug-Food Interactions

Avoid high protein foods that may interfere with phenylalanine levels.

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor blood phenylalanine levels regularly, especially during dose adjustments.

Diagnoses:

Risk for ineffective therapeutic regimen management related to dietary restrictions and medication adherence.

Implementation: Administer as prescribed, monitor for adverse effects, and educate patient on diet and medication adherence.

Evaluation: Assess phenylalanine levels periodically to determine therapeutic response.

Patient/Family Teaching

Take medication exactly as prescribed.
Maintain dietary restrictions as advised.
Report any allergic reactions or adverse effects immediately.
Attend regular follow-up appointments for blood level monitoring.

Special Considerations

Black Box Warnings: N/A

Genetic Factors: Efficacy depends on BH4-responsiveness, which can be determined by a BH4 loading test.

Lab Test Interference: No significant interference reported.

Overdose Management

Signs/Symptoms: Nausea, vomiting, dizziness, hypophenylalaninemia symptoms.

Treatment: Supportive care; discontinue medication; provide symptomatic treatment.

Storage and Handling

Storage: Store at room temperature (20-25°C), away from light and moisture.

Stability: Stable for 24 months under recommended conditions.