Sodium Phenylbutyrate

Pharmacogenomic Information in the Context of the FDA-Approved Drug Label*

Sodium phenylbutyrate is a pro-drug that is rapidly metabolized to phenylacetate. Phenylacetate then conjugates with glutamine via acetylation to form phenylacetylglutamine which can be excreted by the kidneys. Phenylacetylglutamine provides an alternate vehicle to urea for waste nitrogen excretion in patients with urea cycle disorders. Urea cycle disorders may be caused by mutations in the genes CPS1, OTC and ASS1.

The FDA recommends, but does not require, genetic testing prior to initiating or reinitiating treatment with Sodium Phenylbutyrate.

Excerpt from the Sodium Phenylbutyrate (Buphenyl) drug label:
"BUPHENYL® is indicated as adjunctive therapy in the chronic management of patients with urea cycle disorders involving deficiencies of carbamylphosphate synthetase (CPS), ornithine transcarbamylase (OTC), or argininosuccinic acid synthetase (AS)."

For the complete drug label text with sections containing pharmacogenetic information highlighted, see the Sodium Phenylbutyrate (Buphenyl) drug label PDF.