The purpose of this study is to determine if implitapide, used in conjunction with other lipid-lowering therapies, is safe and effective when compared to placebo in lowering low-density lipoprotein cholesterol (LDL-C) in patients with heterozygous familial hypercholesterolemia (HeFH).

Inclusion Criteria:

In order to participate in this study, patients must meet all of the following inclusion criteria:

• be between 18 and 70 years old with a diagnosis of HeFH;
• be stable on and maintain concomitant therapy with hypolipidemic drugs or treatments;
• have an appropriate calculated, fasting LDL-C levels and an appropriate triglyceride (TG) level;
• be male or nonpregnant, nonlactating female;
• give informed consent; and
• meet body weight requirements.

Exclusion Criteria:

In order to participate in this study, patients must not meet any of the following exclusion criteria:

• recent myocardial infarction, percutaneous transluminal coronary intervention, coronary artery bypass graft surgery, or cerebrovascular accident;
• uncontrolled hypothyroidism or other uncontrolled endocrine disease;
• known, clinically significant eye abnormalities (e.g., cataracts);
• appropriate serum creatinine phosphokinase levels;
• history of liver disease or liver enzyme levels above appropriate levels;
• alkaline phosphatase above appropriate levels;
• serum creatinine above appropriate levels;
• liver cirrhosis and severe liver steatosis;
• clinically significant infection, malignancy, or psychosis;
• use of oral anticoagulants or digoxin, unless the dose has been stable for 4 weeks;
• participation in any other investigational study, including device or observational studies, within 30 days;
• lactating or have a positive serum pregnancy test;
• current drug or alcohol abuse; or
• unwillingness to comply with study procedures, including follow-up, as specified by this protocol, or unwillingness to cooperate fully with the investigator