RT Journal Article T1 Switching to Glycerol Phenylbutyrate in 48 Patients with Urea Cycle Disorders: Clinical Experience in Spain. A1 Martín-Hernández, Elena A1 Quijada-Fraile, Pilar A1 Correcher, Patricia A1 Meavilla, Silvia A1 Sánchez-Pintos, Paula A1 de Las Heras Montero, Javier A1 Blasco-Alonso, Javier A1 Dougherty, Lucy A1 Marquez, Ana A1 Peña-Quintana, Luis A1 Cañedo, Elvira A1 García-Jimenez, María Concepción A1 Moreno Lozano, Pedro Juan A1 Murray Hurtado, Mercedes A1 Camprodon Gómez, María A1 Barrio-Carreras, Delia A1 de Los Santos, Mariela A1 Del Toro, Mireia A1 Couce, María L A1 Vitoria Miñana, Isidro A1 Morales Conejo, Montserrat A1 Bellusci, Marcello K1 clinical practice K1 glycerol phenylbutyrate (GPB) K1 sodium benzoate (NaBZ) K1 sodium phenylbutyrate (NaPB) K1 urea cycle disorders (UCDs) AB Background and objectives: Glycerol phenylbutyrate (GPB) has demonstrated safety and efficacy in patients with urea cycle disorders (UCDs) by means of its clinical trial program, but there are limited data in clinical practice. In order to analyze the efficacy and safety of GPB in clinical practice, here we present a national Spanish experience after direct switching from another nitrogen scavenger to GPB. Methods: This observational, retrospective, multicenter study was performed in 48 UCD patients (age 11.7 ± 8.2 years) switching to GPB in 13 centers from nine Spanish regions. Clinical, biochemical, and nutritional data were collected at three different times: prior to GPB introduction, at first follow-up assessment, and after one year of GPB treatment. Number of related adverse effects and hyperammonemic crisis 12 months before and after GPB introduction were recorded. Results: GPB was administered at a 247.8 ± 102.1 mg/kg/day dose, compared to 262.6 ± 126.1 mg/kg/day of previous scavenger (46/48 Na-phenylbutyrate). At first follow-up (79 ± 59 days), a statistically significant reduction in ammonia (from 40.2 ± 17.3 to 32.6 ± 13.9 μmol/L, p SN 2077-0383 YR 2022 FD 2022-08-28 LK http://hdl.handle.net/10668/21339 UL http://hdl.handle.net/10668/21339 LA en DS RISalud RD Apr 13, 2025