Arginine therapy shows promise for sickle cell pain

Sickle cell disease is an inherited condition in which the body makes red blood cells containing abnormal hemoglobin, the protein that carries oxygen from the lungs to other cells in the body. This abnormal hemoglobin (hemoglobin S) causes red blood cells to distort into a sickle, or crescent shape that often blocks blood flow in small blood vessels, leading to severe pain and organ damage.

Arginine is an amino acid found in a normal diet, but is also available as a nutritional supplement. Previous work done by the authors identified an acute arginine deficiency in children during pain episodes, with lowest arginine levels found in children with pain severe enough to require hospitalization. A deficiency of nitric oxide, a potent vasodilator, has been identified in sickle cell disease and may contribute to episodes of blocked vessels and pain. Since arginine is a building block of nitric oxide, researchers hypothesized that arginine could be a beneficial treatment for pain related to sickle cell disease.

Previous research by the authors also found that a single dose of arginine given to patients with sickle cell disease and acute pain episodes resulted in a significant dose-dependent increase in plasma nitric oxide concentration.

Building on that knowledge, the current research study was a randomized, double blind placebo control clinical trial of 38 children with sickle cell disease hospitalized for 56 episodes of pain. The research team discovered a 54 percent reduction in the use of opioid pain medication and significantly lower pain scores at hospital discharge in those treated with arginine over those receiving placebo.

The results were published in the journal Haematologica. First author was Claudia R. Morris, MD, Associate Professor of Pediatrics and Emergency Medicine at Emory University School of Medicine. She conducted the study while in her previous position at Children's Hospital & Research Center Oakland, in Oakland, CA, with Dr. Elliott P. Vichinsky, MD and colleagues.

"Episodes of pain due to vaso-occlusion are the leading cause of hospital admission and emergency room visits and are associated with increased mortality, yet there is no effective therapy targeting the underlying cause," says Morris. "Treatment consists only of symptom relief with pain medicines and hydration. There is an urgent need for new therapies for acute sickle cell pain, and a greater than 50 percent reduction in use of opioid pain medication was a remarkable finding."

The study found no problems with safety in the use of arginine therapy. Although the treatment did not result in a significantly shorter length of stay in the hospital, a trending decrease in hospital stay by 17 hours favored the arginine arm. The researchers believe delivering the study drug as early as possible in the emergency department or clinic may have a greater impact on length of stay, since many patients received their first dose of medication more than 24 hours after presenting the emergency department.

A large, multi-center trial is warranted in order to confirm these observations and test the effects of delivering the therapy sooner, they note in the published paper.