sodium phenylbutyrate (Rx)Brand and Other Names:Buphenyl, phenylbutyrate sodium

 
 
 

Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

tablet

  • 500mg

powder for oral suspension

  • 250 g
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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
more...

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

Interaction Checker

sodium phenylbutyrate and

No Results

     
     activity indicator 
    No Interactions Found
    Interactions Found

    Contraindicated

      Serious - Use Alternative

        Significant - Monitor Closely

          Minor

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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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            Formulary

            FormularyPatient Discounts

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            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.
            6 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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