BETAINE ANHYDROUS

Betaine Anhydrous for Oral Solution is an agent for the treatment of homocystinuria. It contains no ingredients other than anhydrous betaine. Betaine Anhydrous for Oral Solution is a white, granular, hygroscopic powder, which is diluted in water and administered orally. The chemical name of betaine anhydrous powder is trimethylglycine. It has a molecular weight of 117.15. The structural formula is: Structural Formula

Betaine Anhydrous for Oral Solution is indicated for the treatment of homocystinuria to decrease elevated homocysteine blood concentrations in pediatric and adult patients. Included within the category of homocystinuria are: • Cystathionine beta-synthase (CBS) deficiency • 5,10-methylenetetrahydrofolate reductase (MTHFR) deficiency • Cobalamin cofactor metabolism (cbl) defect Betaine Anhydrous for Oral Solution is a methylating agent indicated in pediatric and adult patients for the treatment of homocystinuria to decrease elevated homocysteine blood concentrations. Included within the category of homocystinuria are: • Cystathionine beta-synthase (CBS) deficiency • 5,10-methylenetetrahydrofolate reductase (MTHFR) deficiency • Cobalamin cofactor metabolism (cbl) defect

Adults and Pediatric Patients 3 Years of Age and Older • The recommended dosage is 6 grams per day, administered orally in divided doses of 3 grams twice daily. (2.1) Pediatric Patients Less than 3 Years of Age • The recommended starting dosage is 100 mg/kg/day, administered orally in divided doses of 50 mg/kg twice daily, and then increased weekly by 50 mg/kg increments. (2.1) • Monitor patient response by plasma homocysteine concentrations. (2.1) • Increase the dosage gradually until the plasma total homocysteine concentration is undetectable or present only in small amounts. (2.1) Preparation and Administration Instructions • Prescribed amount of Betaine Anhydrous for Oral Solution should be measured with the measuring scoop provided and then dissolved in 4 to 6 ounces of water, juice, milk, or formula until completely dissolved, or mixed with food for immediate ingestion. (2.2) 2.1 Dosage Therapy with Betaine Anhydrous for Oral Solution should be directed by physicians knowledgeable in the management of patients with homocystinuria. Adults and Pediatric Patients 3 Years of Age and Older The recommended dosage is 6 grams per day, administered orally in divided doses of 3 grams twice daily. Pediatric Patients Less than 3 Years of Age The recommended starting dosage is 100 mg/kg/day divided in twice daily doses, and then increased weekly by 50 mg/kg increments. Monitoring Monitor patient response to Betaine Anhydrous for Oral Solution by homocysteine plasma concentration. Increase the dosage in all patients gradually until the plasma total homocysteine concentration is undetectable or present only in small amounts. An initial response in homocysteine plasma concentrations usually occurs within several days and steady state plasma concentrations occur within a month. Monitor plasma methionine concentrations in patients with CBS deficiency [ see Warnings and Precautions (5.1) ]. Maximum Dosage Dosages of up to 20 grams/day have been necessary to control homocysteine concentrations in some patients. However, one pharmacokinetic and pharmacodynamic in vitro simulation study indicated minimal benefit from exceeding a twice-daily dosing schedule and a 150 mg/kg/day dosage for Betaine Anhydrous for Oral Solution. 2.2 Preparation and Administration Instructions Shake bottle lightly before removing cap Measure the number of scoops for the patient's dose with the scoop provided. One level scoop (1.5 cc) is equivalent to 1 gram of betaine anhydrous powder. Mix powder with 4 to 6 ounces (120 to 180 mL) of water, juice, milk, or formula until completely dissolved, or mix with food, then ingest mixture immediately. Always replace the cap tightly after using and protect the bottle from moisture.

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The following serious adverse reactions are described elsewhere in labeling: • Hypermethioninemia and cerebral edema in patients with CBS deficiency [see Warnings and Precautions (5.1)] . Most common adverse reactions (> 2%) are: nausea and gastrointestinal distress, based on physician survey (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 . See 17 for PATIENT COUNSELING INFORMATION. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in 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 practice. The assessment of clinical adverse reactions is based on a survey study of 41 physicians, who treated a total of 111 homocystinuria patients with Betaine Anhydrous for Oral Solution. Adverse reactions were retrospectively recalled and were not collected systematically in this open-label, uncontrolled, physician survey. Thus, this list may not encompass all types of potential adverse reactions, reliably estimate their frequency, or establish a causal relationship to drug exposure. The following adverse reactions were reported (Table 1): Table 1: Number of Patients with Adverse Reactions to Betaine Anhydrous for Oral Solution by Physician Survey Adverse Reactions Number of Patients Nausea 2 Gastrointestinal distress 2 Diarrhea 1 "Bad Taste" 1 "Caused Odor" 1 Questionable pyschological 1 "Aspirated the powder" 1 6.2 Post-marketing Experience The following adverse reactions have been identified during post approval use of Betaine Anhydrous for Oral Solution. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Severe cerebral edema and hypermethioninemia have been reported within 2 weeks to 6 months of starting Betaine Anhydrous for Oral Solution therapy, with complete recovery after discontinuation of Betaine Anhydrous for Oral Solution. All patients who developed cerebral edema had homocystinuria due to CBS deficiency and had severe elevation in plasma methionine concentrations (range 1,000 to 3,000 microM). As cerebral edema has also been reported in patients with hypermethioninemia, secondary hypermethioninemia due to betaine therapy has been postulated as a possible mechanism of action [see Warnings and Precautions (5.1)] . Other adverse reactions include: anorexia, agitation, depression, irritability, personality disorder, sleep disturbed, dental disorders, diarrhea, glossitis, nausea, stomach discomfort, vomiting, hair loss, hives, skin odor abnormalities, and urinary incontinence.