A randomized, double-blind, placebo-controlled, dose-ranging, multi-center study. Following a 6-8 week placebo and dietary-controlled baseline period, approximately 195 men and women with either hypertriglyceridemia or mixed hyperlipidemia with serum triglycerides (TG) > 200 mg/dl (2.26 mmol/l) will be randomized to receive either placebo, 30 mg 1-MNA or 90 mg 1-MNA three times daily for twelve weeks. Lipid and ancillary exploratory parameters will be evaluated at screening, during the baseline period, upon randomisation and throughout the 12-week active treatment period. Additionally, blood samples will be drawn at randomisation and at clinic visits during the active treatment period for sparse sampling population pharmacokinetic assessments. All blood samples for lipid assessments and glucose measurements will be collected following a 12-hour fast. Safety and tolerability will be assessed throughout the trial through the evaluation of physical exams, ECGs, routine hematology and blood chemistry testing, and adverse events.