This is achieved by providing an artificial electron acceptor (such as methylene blue or flavin) for NADPH methemoglobin reductase (RBCs usually dont have one; the presence of methylene blue allows the enzyme to function at 5× normal levels). The NADPH is generated via the hexose monophosphate shunt. Genetically induced chronic low-level methemoglobinemia may be treated with oral methylene blue daily. Also, vitamin C can occasionally reduce cyanosis associated with chronic methemoglobinemia, and may be helpful in settings in which methylene blue is unavailable or contraindicated (e.g., in an individual with G6PD deficiency). Diaphorase (cytochrome b5 reductase) normally contributes only a small percentage of the red blood cells reducing capacity, but can be pharmacologically activated by exogenous cofactors (such as methylene blue) to five times its normal level of activity. Epidemiology
Methemoglobinemia mostly affects infants under 6 months of age (particularly those under 4 months) due to low hepatic production of methemoglobin reductase. The most at-risk populations are those with water sources high in nitrates, such as wells and other water that is not monitored or treated by a water treatment facility. The nitrates can be hazardous to the infants. The link between blue baby syndrome in infants and high nitrate levels is well established for waters exceeding the normal limit of 10 mg/L. However, there is also evidence that breastfeeding is protective in exposed populations. Society and culture
Blue Fugates
The Fugates, a family that lived in the hills of Kentucky, had the hereditary form. They are known as the "Blue Fugates".
Full data from IGNITE4 will become available as the company prepares to submit its New Drug Application (NDA) in the first quarter of 2018 for Eravacycline treatment of Complicated Intra-abdominal Infections. Complicated Urinary Tract infections (IGNITE 2)
The IGNITE 2 trial compared 7 days of IV eravacycline to IV levofloxacin with the option to convert patients in either group to oral therapy after 3 days for cUTI. Overall, eravacyline was inferior to levofloxacin in response rate (60.4 vs 66.9%); however it was noted that patients who completed therapy with the IV formulation had higher response rates, suggesting formulation issues with the oral option. Due to the performance of the IV formulation, an additional phase 3 trial is planned to support a supplemental NDA for the cUTI indication. Complicated Urinary Tract Infections (IGNITE 3)
IGNITE3 is currently ongoing starting January 2017 with expected completion December 2018. This study is evaluating IV eravacycline (1.5 mg/kg every 24 hours) compared to ertapenem (1g every 24 hours) for the treatment of cUTI. IGNITE3 is currently enrolling approximately 1,000 patients who will be randomized 1:1 to receive intravenous eravacycline or ertapenem for a minimum of 5 days, and will then be eligible for transition to oral levofloxacin.