Successful Treatment of Severe Hyperammonemia Using Sodium Phenylacetate Powder Prepared in Hospital Pharmacy

Abstract

In order to treat a hyperammonemic patient with adult-onset type-II citrullinemia (CTLN2), sodium phenylacetate powder was prepared from chemical reagent grade phenylacetic acid in Gunma University Hospital. After purification by recrystalization, phenylacetic acid was neutralized with sodium carbonate and dried at 70 °C under reduced pressure. A solution of the prepared powder produced a single peak of m/z=181.0 (M+Na⁺) in electrospray-ionization-MS spectrogram. The content of phenylacetate was 74% of theoretical value, suggesting the existence of water of crystallization. The content of phenylacetate remained constant for 5 months under dark conditions at room temperature. The prepared sodium phenylacetate powder was orally administered to a 16-year-old patient with CTLN2 at a dosage of 12 g/d. The serum ammonia concentration of the patient, who did not show adequate response to intravenous arginine or oral sodium benzoic acid decreased remarkably to less than 100 μg/dl. Sodium phenylacetate powder should be an essential drug for the treatment of hyperammonemia caused by an inborn error of the urea cycle.