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Quick facts
- How it is given
- oral
- Type
- human prescription drug
- RxNorm ID
- 1486687
We do not publish dosing. How much of this medicine to take, how often, and for how long depends on your age, weight, kidney and liver function, other conditions and other medicines. That is a decision for the person who prescribes or dispenses it. Follow the directions on your own pack and ask your pharmacist if anything is unclear.
What it is used to treat
Sapropterin dihydrochloride tablets are indicated to reduce blood phenylalanine (Phe) levels in adult and pediatric patients one month of age and older with hyperphenylalaninemia (HPA) due to tetrahydrobiopterin- (BH4-) responsive Phenylketonuria (PKU). Sapropterin dihydrochloride tablets are to be used in conjunction with a Phe-restricted diet. Sapropterin dihydrochloride tablets are a phenylalanine hydroxylase activator indicated to reduce blood phenylalanine (Phe) levels in adult and pediatric patients one month of age and older with hyperphenylalaninemia (HPA) due to tetrahydrobiopterin- (BH4-) responsive Phenylketonuria (PKU). Sapropterin dihydrochloride tablets are to be used in conjunction with a Phe-restricted diet. ( 1 )
About this medicine
Sapropterin dihydrochloride tablets are an orally administered Phenylalanine Hydroxylase activator (or PAH activator). Sapropterin dihydrochloride, the active pharmaceutical ingredient in sapropterin dihydrochloride tablets, is a synthetic preparation of the dihydrochloride salt of naturally occurring tetrahydrobiopterin (BH4). Sapropterin dihydrochloride is an off-white to pale yellow crystalline powder. The chemical name of sapropterin dihydrochloride is (6R)-2-amino-6-[(1R,2S)-1,2-dihydroxypropyl]-5,6,7,8-tetrahydro-4(1H)-pteridinone dihydrochloride and the molecular formula is C 9 H 15 N 5 O 3 ·2HCl with a molecular weight of 314.17. Sapropterin dihydrochloride has the following structural formula: Sapropterin dihydrochloride is supplied as tablets containing 100 mg of sapropterin dihydrochloride (equivalent to 76.8 mg of sapropterin base). Tablets are off-white to light yellow mottled uncoated round tablets debossed with “S 1” on one side and plain on other side. Each tablet contains the following inactive ingredients: ascorbic acid, crospovidone, dibasic calcium phosphate anhydrous, mannitol, riboflavin and sodium stearyl fumarate. Chemical Structure
How it works
12.1 Mechanism of Action Sapropterin dihydrochloride is a synthetic form of BH4, the cofactor for the enzyme phenylalanine hydroxylase (PAH). PAH hydroxylates Phe through an oxidative reaction to form tyrosine. In patients with PKU, PAH activity is absent or deficient. Treatment with BH4 can activate residual PAH enzyme activity, improve the normal oxidative metabolism of Phe, and decrease Phe levels in some patients.
Warnings and cautions
Hypersensitivity Reactions Including Anaphylaxis : Sapropterin dihydrochloride is not recommended in patients with a history of anaphylaxis to sapropterin dihydrochloride; discontinue treatment in patients who experience anaphylaxis and initiate appropriate medical treatment. Continue dietary Phe restrictions. ( 5.1 ) Upper Gastrointestinal Mucosal Inflammation : Monitor patients for signs and symptoms of these conditions including esophagitis and gastritis. ( 5.2 ) Hypophenylalaninemia : Pediatric patients younger than 7 years treated with sapropterin dihydrochloride doses of 20 mg/kg per day are at increased risk for low levels of blood Phe compared with patients 7 years and older. ( 5.3 ) Monitoring Blood Phe Levels During Treatment : Ensure adequate blood Phe control and nutritional balance during treatment with sapropterin dihydrochloride. Frequent blood monitoring is recommended, especially in pediatric patients. ( 5.4 , 2.1 ) Lack of Biochemical Response to sapropterin dihydrochloride Treatment : Response to sapropterin dihydrochloride treatment cannot be pre-determined by laboratory (e.g., molecular) testing and can only be determined by a therapeutic trial of sapropterin dihydrochloride. ( 5.5 , 2.1 ) Interaction with Levodopa : Seizures, over-stimulation or irritability may occur; monitor patients for a change in neurologic status. ( 5.6 , 7 ) Hyperactivity : Monitor patients for hyperactivity. ( 5.7 ) 5.1 Hypersensitivity Reactions Including Anaphylaxis Sapropterin dihydrochloride is not recommended in patients with a history of anaphylaxis to sapropterin dihydrochloride. Hypersensitivity reactions, including anaphylaxis and rash, have occurred [see Adverse Reactions (6.2) ]. Signs of anaphylaxis include wheezing, dyspnea, coughing, hypotension, flushing, nausea, and rash. Discontinue treatment with sapropterin dihydrochloride in patients who experience anaphylaxis and initiate appropriate medical treatment. Continue dietary protein and Phe restriction in patients who experience anaphylaxis. […]
Reported side effects
Most common adverse reactions (≥4%) are: headache, rhinorrhea, pharyngolaryngeal pain, diarrhea, vomiting, cough, and nasal congestion. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Aurobindo Pharma USA, Inc. at 1-866-850-2876, or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to the rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice. PKU Clinical Studies The safety of sapropterin dihydrochloride was evaluated in 7 clinical studies in patients with PKU (aged 1 month to 50 years) [see Clinical Studies (14) ] . In Studies 1 to 4 (controlled and uncontrolled studies), 579 patients with PKU aged 4 to 49 years received sapropterin dihydrochloride in doses ranging from 5 to 20 mg/kg per day for lengths of treatment ranging from 1 to 164 weeks. The patient population was evenly distributed in gender, and approximately 95% of patients were Caucasian. The most common adverse reactions (≥4% of patients) were headache, rhinorrhea, pharyngolaryngeal pain, diarrhea, vomiting, cough, and nasal congestion. The data described in Table 3 reflect exposure of 74 patients with PKU to sapropterin dihydrochloride at doses of 10 to 20 mg/kg per day for 6 to 10 weeks in two double-blind, placebo-controlled clinical trials (Studies 2 and 4). Table 3 enumerates adverse reactions occurring in at least 4% of patients treated with sapropterin dihydrochloride in the double-blind, placebo-controlled clinical trials described above. Table 3: Summary of Adverse Reactions Occurring in ≥4% of Patients in Placebo-Controlled Clinical Studies with Sapropterin Dihydrochloride MedDRA Preferred Term Treatment Sapropterin dihydrochloride (N=74) Placebo (N=59) No. Patients (%) No. […]
Interactions with other medicines
Table 4 includes drugs with clinically important drug interactions when administered with sapropterin dihydrochloride and instructions for preventing or managing them. Table 4: Clinically Relevant Drug Interactions Levodopa Clinical Impact Sapropterin dihydrochloride may increase the availability of tyrosine, a precursor of levodopa. Neurologic events were reported postmarketing in patients receiving sapropterin and levodopa concomitantly for a non- PKU indication [see Warnings and Precautions (5.5) ]. Intervention Monitor patients for a change in neurologic status. Inhibitors of Folate Synthesis (e.g., methotrexate, valproic acid, phenobarbital, trimethoprim) Clinical Impact In vitro and in vivo nonclinical data suggest that drugs that inhibit folate synthesis may decrease the bioavailability of endogenous BH4 by inhibiting the enzyme dihydrofolate reductase, which is involved in the recycling (regeneration) of BH4. This reduction in net BH4 levels may increase Phe levels. Intervention Consider monitoring blood Phe levels more frequently during concomitant administration. An increased dosage of sapropterin dihydrochloride may be necessary to achieve a biochemical response. Drugs Affecting Nitric Oxide-Mediated Vasorelaxation (e.g., PDE-5 inhibitors such as sildenafil, vardenafil, or tadalafil) Clinical Impact Both sapropterin dihydrochloride and PDE-5 inhibitors may induce vasorelaxation. A reduction in blood pressure could occur; however, the combined use of these medications has not been evaluated in humans. Intervention Monitor blood pressure. Inhibitors of Folate Synthesis (e.g., methotrexate, valproic acid, phenobarbital, trimethoprim) : Can decrease endogenous BH4 levels; monitor blood Phe levels more frequently and adjust sapropterin dihydrochloride dosage as needed. ( 7 ) Drugs Affecting Nitric Oxide-Mediated Vasorelaxation (e.g., PDE-5 inhibitors) : Potential for vasorelaxation; monitor blood pressure. ( 7 )
Use in specific groups
8.1 Pregnancy Risk Summary Available data from pregnancy safety studies, pharmacovigilance, and published case reports with sapropterin dihydrochloride use during pregnancy have not identified a drug-associated risk of major birth defects, miscarriage, or adverse maternal or fetal outcomes (see Data). Uncontrolled blood phenylalanine concentrations before and during pregnancy are associated with an increased risk of adverse pregnancy outcomes and fetal adverse effects (see Clinical Considerations). An embryo-fetal development study with sapropterin dihydrochloride in rats using oral doses up to 3 times the maximum recommended human dose (MRHD) given during the period of organogenesis showed no effects. In a rabbit study using oral administration of sapropterin dihydrochloride during the period of organogenesis, a rare defect, holoprosencephaly, was noted at 10 times the MRHD. All pregnancies have a background risk of major birth defects, pregnancy loss, or other adverse pregnancy outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively. The estimated background risk of major birth defects and miscarriage in pregnant women with PKU who maintain blood phenylalanine concentrations greater than 600 micromol/L during pregnancy is greater than the corresponding background risk for pregnant women without PKU. Clinical Considerations Disease-Associated Maternal and/or Embryo-Fetal Risk Uncontrolled blood phenylalanine concentrations before and during pregnancy are associated with an increased risk of adverse pregnancy outcomes and fetal adverse effects. To reduce the risk of hyperphenylalaninemia-induced fetal adverse effects, blood phenylalanine concentrations should be maintained between 120 and 360 micromol/L during pregnancy and during the 3 months before conception [see Dosage and Administration (2.2) ]. […]
If too much is taken
Two unintentional overdosages with sapropterin dihydrochloride have been reported. One adult patient in a sapropterin dihydrochloride clinical trial received a single sapropterin dihydrochloride dose of 4,500 mg (36 mg/kg) instead of 2,600 mg (20 mg/kg). The patient reported mild headache and mild dizziness immediately after taking the dose; both symptoms resolved within 1 hour with no treatment intervention. There were no associated laboratory test abnormalities. The patient suspended therapy for 24 hours and then restarted sapropterin dihydrochloride with no reports of abnormal signs or symptoms. In postmarketing, one pediatric patient received sapropterin dihydrochloride doses of 45 mg/kg per day instead of 20 mg/kg per day. The patient reported hyperactivity that began at an unspecified time after overdosage and resolved after the sapropterin dihydrochloride dose was reduced to 20 mg/kg per day. In a clinical study to evaluate the effects of sapropterin dihydrochloride on cardiac repolarization, a single supra-therapeutic dose of 100 mg/kg (5 times the maximum recommended dose) was administered to 54 healthy adults. No serious adverse reactions were reported during the study. The only adverse reactions reported in more than 1 subject who received the supra-therapeutic dose were upper abdominal pain (6%) and dizziness (4%). A dose-dependent shortening of the QT interval was observed [see Clinical Pharmacology (12.2) ]. Patients should be advised to notify their physicians in cases of overdosage.
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This page is built from the openFDA record of the U.S. Food and Drug Administration's approved labelling for this product, effective 10 June 2025. Label text has been shortened and reformatted for readability; safety wording has not been altered in meaning. FDA labelling describes products approved in the United States — brand names, strengths, formulations and approved uses may differ in your country. Always read the leaflet that comes with your own pack. PocketsInfo is not affiliated with, and is not endorsed by, the FDA. Retrieved 2026-07-30.