NITISINONE

Nitisinone capsules contain nitisinone, which is a 4-hydroxyphenyl-pyruvate dioxygenase inhibitor indicated as an adjunct to dietary restriction of tyrosine and phenylalanine in the treatment of hereditary tyrosinemia type 1 (HT-1). Nitisinone occurs as white to yellowish-white, crystalline powder. It is Freely soluble in Acetone, Ethyl acetate and Methylene chloride. Sparingly soluble in absolute alcohol and practically insoluble in water Chemically, nitisinone is 2-(2-nitro-4-trifluoromethylbenzoyl)- 1,3-cyclohexanedione, and the structural formula is: Figure 1. The molecular formula is C14H10F3NO5 with a relative mass of 329.23 Capsules: Hard, white-opaque capsule, 2 mg, 5 mg, 10 mg, and 20 mg strengths of nitisinone, intended for oral administration. Each capsule contains 2 mg, 5 mg, 10 mg, or 20 mg nitisinone, anhydrous lactose and stearic acid. The capsule shell contains gelatin and titanium dioxide, and the imprinting ink contains black iron oxide, propylene glycol, potassium hydroxide, shellac, and strong ammonia solution. Structural Formula

HIGHLIGHTS OF PRESCRIBING INFORMATION These highlights do not include all the information needed to use NITISINONE CAPSULES safely and effectively. See full prescribing information for NITISINONE CAPSULES. NITISINONE Capsules, for oral use Initial U.S. Approval: 2002 1. INDICATIONS AND USAGE Nitisinone Capsules is indicated for the treatment of adult and pediatric patients with hereditary tyrosinemia type 1 (HT-1) in combination with dietary restriction of tyrosine and phenylalanine. Nitisinone is a hydroxy-phenylpyruvate dioxygenase inhibitor indicated for the treatment of adult and pediatric patients with hereditary tyrosinemia type 1 (HT-1) in combination with dietary restriction of tyrosine and phenylalanine.

Recommended Dosage (2.1): The recommended starting dosage is 0.5 mg/kg orally twice daily. In patients 5 years of age and older who have undetectable serum and urine succinylacetone concentrations after a minimum of 4 weeks on a stable dosage of nitisinone, the total daily dose may be given once daily. Titrate the dosage based on biochemical and/or clinical response, as described in the full prescribing information. The maximum total daily dosage is 2 mg/kg orally. Administration Instructions (2.2): Maintain dietary restriction of tyrosine and phenylalanine Take Nitisinone Capsules at least one hour before, or two hours after a meal For patients who have difficulties swallowing capsules, the capsules may be opened and the contents suspended in a small amount of water, formula, or apple sauce immediately before use. 2.1 Dosage Starting Dosage The recommended starting dosage of Nitisinone Capsules is 0.5 mg/kg administered orally twice daily. Maintenance Regimen In patients 5 years of age and older who have undetectable serum and urine succinylacetone concentrations after a minimum of 4 weeks on a stable dosage of nitisinone, the total daily dose of Nitisinone Capsules may be given once daily (e.g., 1 to 2 mg/kg once daily) [see Clinical Pharmacology (12.2)] . Dosage Titration Titrate the dosage in each individual patient based on biochemical and/or clinical response. Monitor plasma and/or urine succinylacetone concentrations, liver function parameters and alpha-fetoprotein levels. If succinylacetone is still detectable in blood or urine 4 weeks after the start of nitisinone treatment, increase the nitisinone dosage to 0.75 mg/kg twice daily. A maximum total daily dosage of 2 mg/kg may be needed based on the evaluation of all biochemical parameters. If the biochemical response is satisfactory (undetectable blood and/or urine succinylacetone), the dosage should be adjusted only according to body weight gain and not according to plasma tyrosine levels. During initiation of therapy, when switching from twice daily to once daily dosing, or if there is a deterioration in the patient’s condition, it may be necessary to follow all available biochemical parameters more closely (i.e. plasma and/or urine succinylacetone, urine 5- aminolevulinate (ALA) and erythrocyte porphobilinogen (PBG)-synthase activity). Maintain plasma tyrosine levels below 500 micromol/L by dietary restriction of tyrosine and phenylalanine intake [see Warnings and Precautions (5.1)] . In patients who develop plasma tyrosine levels above 500 micromol/L, assess dietary tyrosine and phenylalanine intake. Do not adjust the Nitisinone Capsules dosage in order to lower the plasma tyrosine concentration. 2.2 Administration Instructions Administration of Nitisinone Capsules Maintain dietary restriction of tyrosine and phenylalanine when taking Nitisinone Capsules. Capsules : Take at least one hour before, or two hours after a meal [see Clinical Pharmacology (12.3)] . For patients who have difficulty swallowing the capsules, the capsules may be opened and the contents suspended in a small amount of water, formula or apple sauce immediately before use.

CONTRAINDICATION None. None

Most common adverse reactions (>1%) are elevated tyrosine levels, thrombocytopenia, leukopenia, conjunctivitis, corneal opacity, keratitis, photophobia, eye pain, blepharitis, cataracts, granulocytopenia, epistaxis, pruritus, exfoliative dermatitis, dry skin, maculopapular rash and alopecia. (6.1) To report SUSPECTED ADVERSE REACTIONS, contact Eton Pharmaceuticals, Inc., at 1-855-224-0233 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 rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice. Nitisinone was studied in one open-label, uncontrolled study of 207 patients with HT-1, ages 0 to 22 years at enrollment (median age 9 months), who were diagnosed with HT-1 by the presence of succinylacetone in the urine or plasma. The starting dose of nitisinone was 0.3 to 0.5 mg/kg twice daily, and the dose was increased in some patients to 1 mg/kg twice daily based on weight, biochemical, and enzyme markers. The recommended starting dosage of nitisinone is 0.5 mg/kg twice daily [see Dosage and Administration (2.1)] . Median duration of treatment was 22 months (range 0.1 to 80 months). The most serious adverse reactions reported during nitisinone treatment were thrombocytopenia, leukopenia, porphyria, and ocular/visual complaints associated with elevated tyrosine levels [see Warnings and Precautions (5.1, 5.2)] . Fourteen patients experienced ocular/visual events. The duration of the symptoms varied from 5 daysto 2 years. Six patients had thrombocytopenia, three of which had platelet counts 30,000/microL or lower. In 4 patients with thrombocytopenia, platelet counts gradually returned to normal (duration up to 47 days) without change in nitisinone dose. No patients developed infections or bleeding as a result of the episodes of leukopenia and thrombocytopenia. Patients with HT- 1 are at increased risk of developing porphyric crises, hepatic neoplasms, and liver failure requiring liver transplantation. These complications of HT- 1 were observed in patients treated with nitisinone for a median of 22 months during the clinical trial (liver transplantation 13%, liver failure 7%, malignant hepatic neoplasms 5%, benign hepatic neoplasms 3%, porphyria 1%). The most common adverse reactions reported in the clinical trial are summarized in Table 1. Table 1: Most Common Adverse Reactions in Patients with HT-1 Treated with Nitisinone* Elevated tyrosine levels >10% Leukopenia 3% Thrombocytopenia 3% Conjunctivitis 2% Corneal opacity 2% Keratitis 2% Photophobia 2% Eye pain 1% Blepharitis 1% Cataracts 1% Granulocytopenia 1% Epistaxis 1% Pruritus 1% Exfoliate dermatitis 1% Dry skin 1% Maculopapular rash 1% Alopecia 1% *reported in at least 1% of patients Adverse reactions reported in less than 1% of the patients, included death, seizure, brain tumor, encephalopathy, hyperkinesia, cyanosis, abdominal pain, diarrhea, enanthema, gastrointestinal hemorrhage, melena, elevated hepatic enzymes, liver enlargement, hypoglycemia, septicemia, and bronchitis.

Nitisinone is a moderate CYP2C9 inhibitor, a weak CYP2E1 inducer and an inhibitor of OAT1/OAT3. Table 2 includes drugs with clinically important drug interactions when administered concomitantly with nitisinone and instructions for preventing or managing them. Table 2: Clinically Relevant Interactions Affecting Co-Administered Drugs Sensitive CYP2C9 Substrates (e.g., celecoxib, tolbutamide) or CYP2C9 Substrates with a Narrow Therapeutic Index (e.g., phenytoin, warfarin) Clinical Impact Increased exposure of the co-administered drugs metabolized by CYP2C9 [see Clinical Pharmacology (12.3)]. Intervention Reduce the dosage of the co-administered drugs metabolized by CYP2C9 drug by half. Additional dosage adjustments may be needed to maintain therapeutic drug concentrations for narrow therapeutic index drugs. See prescribing information for those drugs. OAT1/OAT3 Substrates (e.g., adefovir, ganciclovir, methotrexate) Clinical Impact Increased exposure of the interacting drug [see Clinical Pharmacology (12.3)]. Intervention Monitor for potential adverse reactions related to the co-administered drug. CYP2C9 Substrates: Increased systemic exposure of these co-administered drugs; reduce the dosage. Additional dosage adjustments may be needed to maintain therapeutic drug concentrations for narrow therapeutic index drugs. OAT1/OAT3 Substrates: Increased systemic exposure of these co-administered drugs; monitor for potential adverse reactions. See 17 for PATIENT COUNSELING INFORMATION and FDA approved patient labeling. Revised 02/2024