Sodium Phenylbutyrate Tablets

Dosage form: tablet
Drug class:Urea cycle disorder agents

Medically reviewed by Drugs.com. Last updated on Jun 21, 2021.

Sodium Phenylbutyrate Tablets Description

Sodium Phenylbutyrate Tablets for oral administration contain Sodium phenylbutyrate, USP. Sodium Phenylbutyrate, USP is an off-white crystalline substance which is soluble in water and has a strong salty taste. Sodium Phenylbutyrate, USP also is freely soluble in methanol and practically insoluble in acetone and diethyl ether. It is known chemically as 4-phenylbutyric acid, sodium salt with a molecular weight of 186 and the molecular formula C10H11O2Na.

Chemical Structure:

Each tablet of Sodium Phenylbutyrate Tablets contains 500 mg of Sodium Phenylbutyrate, USP and the inactive ingredients calcium stearate NF, colloidal silicon dioxide NF, magnesium stearate and microcrystalline cellulose.

Sodium Phenylbutyrate Tablets - Clinical Pharmacology

Sodium phenylbutyrate is a pro-drug and is rapidly metabolized to phenylacetate. Phenylacetate is a metabolically-active compound that conjugates with glutamine via acetylation to form phenylacetylglutamine. Phenylacetylglutamine then is excreted by the kidneys. On a molar basis, it is comparable to urea (each containing two moles of nitrogen). Therefore, phenylacetylglutamine provides an alternate vehicle for waste nitrogen excretion.

PHARMACOKINETICS

General:

Pharmacokinetic studies have not been conducted in the primary patient population (neonates, infants, and children), but pharmacokinetic data were obtained from normal adult subjects.

Absorption:

Peak plasma levels of phenylbutyrate occur within 1 hour after a single dose of 5 grams of sodium phenylbutyrate tablet with a Cmax of 218 mcg/mL under fasting conditions. The effect of food on phenylbutyrate's absorption is unknown.

Disposition:

The overall disposition of sodium phenylbutyrate and its metabolites has not been characterized fully. However, the drug is known to be metabolized to phenylacetate and subsequently to phenylacetylglutamine.

Following oral administration of 5 grams (tablets), measurable plasma levels of phenylbutyrate a...