Arginine Therapy for Sickle Cell Disease Acute Pain Episodes

Importance: Acute pain episodes are the leading cause of emergency department visits and hospitalizations for patients with sickle cell disease (SCD), yet US Food and Drug Administration-approved drugs for acute pain episodes are lacking. During acute pain episodes, patients develop acute arginine deficiency associated with longer time to crisis resolution and greater total parenteral opioid use. Multiple single-center, phase 2 randomized clinical trials have shown that arginine is safe, is opioid sparing, improves cardiopulmonary function, and reduces length of hospital stay. Objective: To determine the efficacy and safety of intravenous arginine for SCD acute pain episodes. Design, Setting, and Participants: Prospective, phase 3, double-blind randomized clinical trial conducted between June 21, 2021, and June 13, 2024, in 10 US children's hospitals enrolling patients aged 3 to 21 years presenting to the emergency department with SCD acute pain episodes requiring parenteral opioids. Interventions: Patients were randomized to receive intravenous arginine (200 mg/kg followed by 100 mg/kg every 8 hours until discharge; n = 129) or saline placebo (n = 142). Main Outcomes and Measures: The primary outcome was time to crisis resolution, defined as hours from initial study drug delivery to last intravenous opioid dose. Secondary outcomes included total parenteral opioid use (intravenous morphine equivalents in milligrams per kilogram from first study drug dose to last intravenous opioid dose), pain scores, and patient-reported outcomes. Results: Of 274 randomized participants, 271 received study drug; the mean age was 14.3 years (SD, 4.3 years), 51% were male, and 92% were Black. The trial was halted early for futility, as time to crisis resolution was similar in those receiving arginine vs placebo (median, 60.8 hours [IQR, 34.8-109.0 hours] vs 65.8 hours [IQR, 31.1-111.1 hours], respectively; absolute difference, 7.2 hours; 95% CI, -21.6 to 35.9 hours). No significant differences were seen in total parenteral opioid use, pain scores, patient-reported outcomes, or safety events. Conclusions and Relevance: Arginine therapy did not shorten time to crisis resolution compared with placebo among children and young adults with SCD acute pain episodes. Trial Registration: ClinicalTrials.gov Identifier: NCT04839354.