sodium phenylbutyrate (Rx)

Brand and Other Names:Buphenyl, phenylbutyrate sodium
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Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

tablet

  • 500mg

powder for oral suspension

  • 250 g

Urea Cycle Disorders

Indicated as an adjunct to dietary protein restriction and essential amino acid supplementation for the chronic management of patients with urea cycle disorders involving deficiencies of carbamylphosphate synthetase (CPS), ornithine transcarbamylase (OTC), or argininosuccinic acid synthetase (AS)

It is indicated in all patients with neonatal-onset deficiency (complete enzymatic deficiency, presenting within the first 28 days of life) and for late-onset disease (partial enzymatic deficiency, presenting after the first month of life) who have a history of hyperammonemic encephalopathy

9.9-13 g/m² PO divided q4-8hr PO; not to exceed 20 g/day  

Dosing Considerations

Must be combined with dietary protein restriction and, in some cases, essential amino acid supplementation

Monitor plasma amino acids, ammonia

Sickling Disorders (Orphan)

Orphan designated treatment of disorders including hemoglobinopathies S-S, S-C, and S-thalassemia

Orphan sponsor

  • Medicis Pharmaceutical Corp; 8125 N. Hayden Rd; Scottsdale, AZ 85258

Malignant Glioma (Orphan)

Orphan designation for adjunct to surgery, radiation, & chemotherapy in the treatment of primary or recurrent malignant glioma

Orphan sponsor

  • Elan Drug Delivery, Inc; 1300 Gould Dr; Gainesville, GA 30504

Spinal Muscular Atrophy (Orphan)

Orphan designation for treatment of spinal muscular atrophy

Orphan sponsors

  • Ucyclyd Pharma, Inc; 7720 N. Dobson Rd; Scottsdale, AZ 85256
  • Tikvah Therapeutics, Inc; 75 5th St, NW; Atlanta, GA 30308
  • GMP-Orphan SAS; 7, rue du Pasteur Wagner, F-75011; Paris, France

Dosing Considerations

Must be combined with dietary protein restriction and, in some cases, essential amino acid supplementation

Monitor plasma amino acids, ammonia

Administration

Take with food in equally divided doses with meals (ie, 3-6 times/day)

Mix powder with solid or liquid food but NOT acidic beverages (eg, orange juice)

Dosage Forms & Strengths

tablet

  • 500mg

powder for oral suspension

  • 250 mg

Urea Cycle Disorders

Indicated as an adjunct to dietary protein restriction and essential amino acid supplementation for the chronic management of patients with urea cycle disorders involving deficiencies of carbamylphosphate synthetase (CPS), ornithine transcarbamylase (OTC), or argininosuccinic acid synthetase (AS)

It is indicated in all patients with neonatal-onset deficiency (complete enzymatic deficiency, presenting within the first 28 days of life) and for late-onset disease (partial enzymatic deficiency, presenting after the first month of life) who have a history of hyperammonemic encephalopathy

≥20 kg (tablet or suspension): 9.9-13 g/m² PO divided q4-8hr PO; not to exceed 20 g/day

<20 kg (suspension): 450-600 mg/kg/day divided q4 -6hr PO (solution only)  

Administration

Take with food in equally divided doses with meals or feedings (ie, 3-6 times/day)

Mix powder with solid or liquid food but NOT acidic beverages (eg, orange juice)

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Interactions

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                • probenecid

                  probenecid increases levels of sodium phenylbutyrate by decreasing renal clearance. Use Caution/Monitor.

                Minor (0)

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                  Adverse Effects

                  >10%

                  Amenorrhea/dysmenorrhea (23%)

                  Hypoalbuminemia (11%)

                  Metabolic acidosis (14%)

                  1-10%

                  Anemia (9%)

                  Anorexia (4%)

                  Hypophosphatemia (2%)

                  Hypernatremia (1%)

                  Hyperuricemia (2%)

                  Hypokalemia (1%)

                  Leukopenia (4%)

                  Strong body odor (3%)

                  Thrombocytopenia (3%)

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                  Warnings

                  Contraindications

                  Hypersensitivity

                  Acute hyperammonemia

                  Cautions

                  Renal insufficiency, hepatic insufficicency, CHF

                  Patients on restricted sodium intake (contains 125 mg Na/g)

                  Powder should not be mixed with acidic liquids

                  May cause sodium and fluid retention; caution in patients that poorly tolerate fluid retention like those with heart failure

                  Hyperammonemia and hyperammonemic encephalopathy may occur while on therapy (manage hyperammonemia as a medical emergency

                  Will not reverse existing hyperammonemia-inflicted neurologic damage

                  Low protein diet recommended with possible amino acid substitution

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                  Pregnancy & Lactation

                  Pregnancy Category: C

                  Lactation: Use caution

                  Pregnancy Categories

                  A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

                  B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

                  C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

                  D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

                  X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

                  NA: Information not available.

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                  Pharmacology

                  Mechanism of Action

                  Decreases elevated plasma ammonia glutamine levels

                  Prodrug that is rapidly metabolized to phenylacetate which conjugates with glutamine to form phenylacetylglutamine, a nitrogen waste product that is excreted renally

                  The phenylacetylglutamine conjugate provides an alternate vehicle to urea for waste nitrogen excretion; for each gram of sodium phenylbutyrate administered, it is estimated that between 0.12–0.15 grams of phenylacetylglutamine nitrogen are produced

                  Absorption

                  Peak plasma time: 1-1.35 hr (phenylbutyrate); 3.55-3.74 hr (phenylacetate)

                  Peak plasma concentration: 195-218 mcg/mL (phenylbutyrate); 45.3-48.5 mcg/mL (phenylacetate)

                  Metabolism

                  Sodium phenylbutyrate: Liver, and kidney

                  Elimination

                  Half-life: 0.8 hr (phenylbutyrate); 1.15-1.29 hr (phenylacetate)

                  Excretion: Urine 80-100% (as phenylacetylglutamine)

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                  Images

                  BRAND FORM. UNIT PRICE PILL IMAGE
                  sodium phenylbutyrate oral
                  -
                  0.94 gram/gram powder
                  sodium phenylbutyrate oral
                  -
                  0.94 gram/gram powder
                  Buphenyl oral
                  -
                  500 mg tablet

                  Copyright © 2010 First DataBank, Inc.

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                  Patient Handout

                  Patient Education
                  sodium phenylbutyrate oral

                  SODIUM PHENYLBUTYRATE - ORAL

                  (SO-dee-um fen-ill-BYOU-tih-rate)

                  COMMON BRAND NAME(S): Buphenyl

                  USES: This medication is used along with diet changes for long-term treatment of a certain inherited disorder (urea cycle disorder). It helps remove a certain chemical (ammonia) from the body. Too much ammonia in the body can cause brain damage and sometimes death.This medication should not be used to treat sudden, severely high levels of ammonia in the body. Seek immediate medical attention if you have sudden symptoms of too much ammonia, such as trouble thinking, vomiting, irritability, trouble speaking, trouble walking, fainting.

                  HOW TO USE: Read the Patient Information Leaflet if available from your pharmacist before you start using this medication and each time you get a refill. If you have any questions, ask your doctor or pharmacist.Take this medication by mouth exactly as directed by your doctor. The dosage is based on your weight or body size, medical condition, and response to treatment. The total daily dose should be divided into equal amounts and taken with each meal or feeding (such as 3 to 6 times daily). Do not increase or decrease your dose without your doctor's approval.Use this medication regularly to get the most benefit from it. To help you remember, take it at the same times each day.

                  SIDE EFFECTS: Loss of appetite or menstrual changes (delayed/irregular/absent periods) may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.Tell your doctor right away if you have any serious side effects, including: drowsiness/lightheadedness, easy bruising/bleeding, fast/pounding heartbeat, mental/mood changes, signs of infection (such as sore throat that doesn't go away, fever), tiredness, signs of metabolic imbalance (such as rapid breathing, muscle twitching/spasms).A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

                  PRECAUTIONS: Before taking this medication, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.Before using this medication, tell your doctor or pharmacist your medical history, especially of: a certain heart problem (congestive heart failure), kidney disease, liver disease, swelling (edema).This medication contains salt (sodium). Before taking this medication, tell your doctor or pharmacist if you are on a low-salt diet.This drug may make you drowsy. Alcohol or marijuana (cannabis) can make you more drowsy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.It is unknown if this medication passes into breast milk. Consult your doctor before breast-feeding.

                  DRUG INTERACTIONS: Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

                  OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center.

                  NOTES: Do not share this medication with others.Laboratory and/or medical tests (such as plasma ammonia/amino acid levels, complete blood count, blood chemistries, urine tests, drug levels) should be performed periodically to monitor your progress or check for side effects. Consult your doctor for more details.

                  MISSED DOSE: If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up. It is very important to take the full amount prescribed for each 24-hour period.

                  STORAGE: Store in a tightly closed container at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.

                  Information last revised April 2022. Copyright(c) 2022 First Databank, Inc.

                  IMPORTANT: HOW TO USE THIS INFORMATION: This is a summary and does NOT have all possible information about this product. This information does not assure that this product is safe, effective, or appropriate for you. This information is not individual medical advice and does not substitute for the advice of your health care professional. Always ask your health care professional for complete information about this product and your specific health needs.

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                  Formulary

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                  The above information is provided for general informational and educational purposes only. Individual plans may vary and formulary information changes. Contact the applicable plan provider for the most current information.

                  Tier Description
                  1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
                  2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
                  3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
                  4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
                  5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
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                  Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.