The purpose of this study is to determine the effectiveness and safety of TRIA-662 (also known as 1-MNA) in treating elevated triglyceride levels in patients not receiving lipid lowering treatment. This study will determine the effects of TRIA-662 on commonly measured blood fats that are known to be important in the prevention of vascular disease.

This is 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 TRIA-662 or 90 mg TRIA-662 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.

Inclusion Criteria:

• Patients at least 18 years of age at the time of informed consent (women of childbearing potential must be practicing adequate contraception)
• Patients with mean serum TG > 200 mg/dl (2.26 mmol/l) and < 700 mg/dl (7.91 mmol/l) as measured at 2 sequential visits during the dietary controlled baseline period (Visits 2 and 3 or Visits 3 and 3a) and having lower level within 25% of upper level (higher value minus lower value)/higher value < 0.25)
• Patients willing and able to sign an informed consent form and follow the protocol

Exclusion Criteria:

• Patients who are pregnant or nursing
• Patients with evidence of hepatic dysfunction [alanine aminotransferase (ALT) or aspartate aminotransferase (AST) greater than 1.5 times the upper limit of normal (ULN), bilirubin greater than 1.5 times ULN, or cirrhosis] or renal dysfunction (serum creatinine greater than 140 μmol/l, or nephrotic syndrome) as measured during the baseline phase
• Patients with uncontrolled diabetes mellitus (fasting glucose level above 11 mmol/l or HbA1C above 10%) as measured during the baseline phase
• Patients with hypothyroidism that is not treated or not stable for at least 6 months prior to study entry
• Patients with uncontrolled hypertension (systolic blood pressure above 160 mm Hg and/or diastolic blood pressure above 110 mm Hg)
• Patients with systolic blood pressure above 140 mm Hg AND three or more of the following cardiovascular risk factors:
• Current cigarette smoker
• HDL-C < 40 mg/dL (1.04 mmol/L)
• Coronary heart disease in male first degree relative < 55 years of age
• Coronary heart disease in female first degree relative < 65 years of age
• Male age 45 years or older
• Female age 55 years or older
• Patients with known hyperuricemia or with a history of gout
• Patients with an active peptic ulcer
• Patients with known coronary artery disease, cerebrovascular disease or peripheral arterial disease that has previously required percutaneous coronary intervention or surgical intervention
• Patients with known intolerance or allergy to niacin
• Patients consuming more than 10 alcoholic drinks per week
• Patients with a history of drug abuse
• Patients receiving any lipid modifying agent within 4 weeks of entry into the baseline period
• Patients participating in another clinical trial within 30 days of entry into the baseline period
• Patients considered to be non-compliant to study medication (< 80% study medication) or diet during the placebo-baseline phase
• Patients for whom the investigator determines that the study would not be appropriate