Mezzion Pharma Co. Ltd. announced that it has submitted a New Drug Application (NDA) to the U.S. Food and Drug Administration (FDA) for the approval of udenafil to improve the physiology of patients 12 years of age and older with single ventricle heart disease (SVHD) who have undergone the Fontan operation. Udenafil is a long acting highly selective phosphodiesterase-5 inhibitor that is orally administered. The NDA includes a request for Priority Review, which, if granted, may shorten the FDA's review of the NDA to six months from the time of filing, versus a standard review timeline of 10 months from filing. The NDA submission, which totals nearly 100,000 pages, is supported by data from more than 700 documents including more than 200 studies that Mezzion has completed during the last 2 decades since its founding in 2002. The NDA package includes a pivotal Phase 3 clinical study conducted globally in close collaboration with the Pediatric Heart Network (PHN), which is funded by a grant from the National Heart, Lung, and Blood Institute (NHLBI). This was the pharmacotherapeutic study ever to be conducted in those with a congenital heart condition and involved the recruitment and treatment of 400 male and female adolescents from 30 PHN and auxiliary sites throughout the U.S.A., Canada, and the Republic of Korea. The results of this study, the Fontan Udenafil Exercise Longitudinal (FUEL) trial, were published in Circulation (December 2019) abstract #20942. The results of the landmark FUEL trial demonstrated statistically significant improvements in multiple measures of exercise performance and cardiac function in patients treated with udenafil who had undergone the Fontan operation. The improvements in exercise were most pronounced at moderate levels of activity while the improvement in cardiac function was determined using the myocardial performance index, a standard echocardiographic measurement technique.