The NORIG ( Nortriptyline for Idiopathic Gastroparesis ) trial , a 15-week multicenter , parallel-group , placebo-controlled , double-masked , randomized clinical trial from the National Institute of Diabetes and Digestive and Kidney Diseases Gastroparesis Clinical Research Consortium ( GpCRC ) , comparing nortriptyline with placebo for symptomatic relief in idiopathic gastroparesis .