Oral arginine therapy appears safe, effective for sickle cell disease pain management
ORLANDO — Oral supplementation with arginine resulted in faster resolution of pain associated with vaso-occlusive episodes among younger patients with sickle cell disease, according to the results of a randomized phase 2 trial presented at ASH Annual Meeting and Exposition.
The study also showed that patients who had previous arginine supplementation required fewer analgesic agents to control pain and had shorter hospital stays than controls.
“When patients have crisis episodes associated with sickle cell disease, the current mode of treatment is the use of an analgesic, which is mainly for symptomatic control,” Richard Onalo, FCPaed, head of the department of pediatrics at University of Abuja in Nigeria, and one of the study co-authors, told Healio. “However, there is no molecular way to address the genetic basis of sickle cell disease. Arginine is a supplement used by the body that produces a vaso-relaxation effect, and previous studies showed that arginine supplementation is useful in lowering pulmonary hypertension.”
Onalo said the previous findings motivated his group to explore whether arginine supplementation could have a positive effect on pain control during vaso-occlusive crisis episodes in patients with sickle cell disease.
“My country has the highest number of patients with sickle cell disease in the world, so if there are any studies that produce positive results, then they should be done in Nigeria,” Onalo said. “That’s the main reason why we conducted this study.”
Onalo said the key takeaway from the study is that arginine supplementation is safe and demonstrates a fast reduction in pain among patients with sickle cell disease. It also significantly reduced the amount of analgesic needed for treatment during painful episodes.
“We also found that the time to revolve symptoms during crisis was shorter among those patients who received previous arginine supplementation,” Onalo told Healio. “If arginine is used, it produces good clinical outcomes with shorter hospital stays, which translates into savings of time and money treating these patients.”
The blinded, placebo-controlled study was performed at two hospitals in Nigeria and included 68 patients aged 5 to 17 years with sickle cell disease who were admitted to the pediatric unit for vaso-occlusive pain.
Researchers randomly assigned patients to arginine supplementation (n = 35; mean age, 10.7 years; standard deviation [SD], ± 3.3 years; 51% male) or placebo (n = 33; mean age, 10.5 years; SD, ± 3.5 years; 61% male). The arginine and placebo groups had similar baseline characteristics, including pain scores (8.7; SD, ± 1.1 vs. 8.4; SD, ± 1.3).
Patients in the arginine group received a supplement of L-arginine HCL 100 mg/kg in grape juice every 8 hours for 5 days. They had blood samples drawn before administration of the arginine supplement and at discharge from the pediatric unit.
Researchers assessed use of analgesics to treat pain by the Medication Quantification Scale (MQS) tool.
Primary clinical outcomes included change in total analgesic medication required to revolve episodes, differences in pain scores, time-to-crisis resolution and total length of hospital stay.
Results showed a significantly lower MQS score in the arginine group (73; 95% CI, 62-84) at day 5 compared with the placebo group (120; 95% CI, 97-143; P < .001).
Fifty-four percent of patients in the arginine group had improved time-to-crisis resolution (pain score < 4) and were discharged from the pediatric unit by day 5 compared with 24% in the placebo group (P = .02).
The length of hospital stay was 110 hours in the arginine group vs. 156 hours in the placebo group (log-rank chi-square = 10.06; P = .0015).
Baseline pain scores appeared similar between the groups; however, the arginine group had lower reported pain scores than the placebo group at day 5 (1.2; SD,± 0.4 vs. 3; SD, ± 0.5; P < .0001).
Plasma arginine levels increased by 125% in the arginine group compared with 29% in the placebo group.
Investigators observed an inverse correlation of percent increase in bioavailable arginine with MSQ (r = –0.35; P = .02). They also noted a statistically nonsignificant decrease in mean total opioid dose used in the arginine vs. placebo group (3.8 mg/kg vs. 5.1 mg/kg).
There was one death in the placebo group during day 2 of the study.
The investigators observed no serious adverse events among patients who received arginine; however, they did notice a trend toward more frequent vomiting compared with the placebo group (20% vs. 3%).
“Something happens metabolically in patients whereby their arginine levels drop during pain episodes, so if we are treating a nutritional deficiency, acute sickle cell pain is a time of extreme arginine deficiency,” Claudia R. Morris, MD, FAAP, professor of pediatrics and emergency medicine at Emory University School of Medicine, and one of the study’s co-authors, told Healio. “It remains to be seen if there are benefits prophylactically on pain relief during acute pain episodes associated with sickle cell disease.”
“Concrete conclusions about our results can only be made after a phase 3 trial,” Onalo said. “Our results point toward a need for a multicenter study so our outcomes can be verified.” – by Drew Amorosi
Onalo R, et al. Abstract 613. Presented at: ASH Annual Meeting and Exposition; Dec. 7-10, 2019; Orlando.
Disclosures: Morris reports a consultant role with Pfizer and patents owned by UCSF-Benioff Children’s Hospital Oakland for biomarkers and therapies that target bioavailability. Onalo reports no relevant financial disclosures. Please see the abstract for all other authors’ relevant financial disclosures.