Quantification of urinary derivatives of Phenylbutyric and Benzoic acids by LC-MS/MS as treatment compliance biomarkers in Urea Cycle disorders

Fernando Andrade, Isidro Vitoria, Elena Martín Hernández, Guillem Pintos-Morell, Patricia Correcher, Rocío Puig-Piña, Pilar Quijada-Fraile, Luis Peña-Quintana, Ana Mª Marquez, Olatz Villate, Mª Teresa García Silva, Javier de las Heras, Leticia Ceberio, Esmeralda Rodrigues, Teresa Almeida Campos, Raquel Yahyaoui, Javier Blasco, Inmaculada Vives-Piñera, David Gil, Mireia del ToroMónica Ruiz-Pons, Elvira Cañedo, Miguel Angel Barba Romero, Mª Concepción García-Jiménez, Luis Aldámiz-Echevarría

Research output: Contribution to journalArticleResearch

1 Citation (Scopus)


© 2019 Elsevier B.V. Purpose: Salts of phenylacetic acid (PAA) and phenylbutyric acid (PBA) have been used for nitrogen elimination as a treatment for hyperammonaemia caused by urea cycle disorders (UCD). A new analytical method for PBA measurement in urine which helps to evaluate the drug adherence has been implemented. Methods: Urine specimens from UCD patients receiving PBA were analysed by tandem mass spectrometry to measure urine phenylacetylglutamine (PAGln). Some clinical and biochemical data for each patient were collected. Results: Our study included 87 samples from 40 UCD patients. The PAGln levels did not correlate with height, weight or age. However, the PAGln values showed correlation with PBA dose (r = 0.383, P = 0.015). Plasma glutamine and ammonia levels presented a positive correlation (r = 0.537, P < 0.001). The stability for PAGln in urine was determined at different storage temperatures. Conclusions: We have developed a simple method for the determination of PAGln in urine, which acts as useful biomarker of effective drug delivery. PAGln in urine is stable at room temperature at least for 15 days, and for several months when frozen at -20 °C. This procedure is useful for the optimization and monitorization of the drug dose allowing the use of spot urine samples.
Original languageEnglish
Article number112798
JournalJournal of Pharmaceutical and Biomedical Analysis
Publication statusPublished - 30 Nov 2019


  • Benzoic acid
  • Hyperammonaemia
  • Phenylbutyric acid
  • Stability
  • Tandem mass spectrometry
  • Urea cycle disorders


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