The purpose of this study is to evaluate the potential effects of ER niacin/laropiprant, ER niacin, laropiprant, and placebo over the course of seven days on urinary levels of a metabolite of thromboxane A2 (TxA2), as a marker of in vivo platelet reactivity.

Inclusion Criteria:

• Female subjects may not be pregnant and/or will agree to use appropriate method of contraception beginning at least 2 weeks prior to administration of the first dose of study drug in the first treatment period, throughout the study and until at least 2 weeks after administration of the last dose of study drug in the last treatment period.
• Subject is judged to be in good health based on medical history, physical examination, vital sign measurements, and laboratory safety tests performed at the prestudy (screening) visit and/or prior to administration of the initial dose of study drug.
• Subject has no clinically significant abnormality on electrocardiogram (ECG) performed at the prestudy (screening) visit and/or prior to administration of the initial dose of study drug.
• Subject has been a nonsmoker and/or has not used nicotine or nicotine-containing products for at least approximately 6 months; subjects who have discontinued smoking or the use of nicotine/nicotine containing products for at least approximately 3 months may be enrolled in the study at the discretion of the investigator

Exclusion Criteria:

• Subject is mentally or legally incapacitated, has significant emotional problems at the time of prestudy (screening) visit or expected during the conduct of the study or has a history of a clinically significant psychiatric disorder over the last 5 to 10 years. - Subjects who have had situational depression may be enrolled in the study at the discretion of the investigator.
• Subject has a history of stroke, chronic seizures, or major neurological disorder.
• Subject has a history of clinically significant endocrine, gastrointestinal, cardiovascular, hematological, hepatic, immunological, renal, respiratory, or genitourinary abnormalities or diseases.
• Subject has a history of neoplastic disease (including leukemia, lymphoma, malignant melanoma), or myeloproliferative disease, regardless of the time since treatment.
• Subject has history of a thrombotic or platelet related disorder including prior deep venous thrombosis. Subject is being treated with coumadin, heparin, clopidogrel has used these agents within 2 weeks of screening. Subject is being treated with aspirin or has used this agent within 3 weeks prior to administration of screening.
• Subject is unable to refrain from or anticipates the use of any medication, including prescription and non- prescription drugs or herbal remedies beginning approximately 2 weeks prior to administration of the initial dose of study drug, throughout the study until the poststudy visit.
• Subject consumes excessive amounts of alcohol, defined as greater than 3 glasses, of alcoholic beverages or distilled spirits per day.
• Subject consumes excessive amounts, defined as greater than 6 servings, of coffee, tea, cola, or other caffeinated beverages per day.
• Subject has had major surgery, donated or lost 1 unit of blood (approximately 500 mL) or participated in another investigational study within 4 weeks prior to the prestudy (screening) visit.
• Subject has a history of significant multiple and/or severe allergies, or has had an anaphylactic reaction or significant intolerability to prescription or non-prescription drugs or food.
• Subject is currently a regular user of any illicit drugs or has a history of drug (including alcohol) abuse within approximately 6 months.