A Study to Assess the Effect of SB 659032 on Platelet Function

Inclusion Criteria: * Healthy males or females who are 18 to 55 years of age, inclusive. * Body weight greater than 50 kg (110 pounds) and body mass index (BMI) between 19 and 30 where: BMI = weight in kg (height in meters)2 Exclusion Criteria: * Any clinically relevant abnormality identified on the screening medical assessment, laboratory examination or ECG * History of asthma, anaphylaxis or anaphalactoid reactions, severe allergic responses * History of smoking within six months of the study and/or has a positive urine cotinine at screening * History of alcohol consumption exceeding, on average, 7 drinks/week for women or 14 drinks/week for men (1 drink = 5 ounces of wine or 12 ounces of beer or 1.5 ounces of hard liquor) within 6 months of the first dose of study medication * Positive urine drug or alcohol at screening * Use of aspirin, aspirin-containing products, non-steroidal anti-inflammatory agents or any antiplatelet medication within 14 days prior to the first dose of study medication (a list of these drugs will be reviewed with the subject at screening and provided to them to take home) * Use of prescription (including hormone replacement therapy) or non-prescription drugs and vitamins within 7 days or 5 half-lives (whichever is longer) prior to administration of study medication. An exception is acetaminophen which is allowed at doses of less than and equal to 2g/day for up to 48 hours prior to dosing * Use of dietary/herbal supplements including (but not limited to) St. John's wort, kava, ephedra (ma huang), gingko biloba, DHEA, yohimbe, saw palmetto, ginseng and red yeast rice within 14 days prior to treatment with study medication * Treatment with an investigational drug within 30 days or 5 half-lives (whichever is longer) prior to dosing * Consumption of grapefruit or grapefruit juice within 7 days prior to the first dose of study medication * A history of biliary tract disease including a history of liver disease with elevated liver function tests of known or unknown etiology * Pregnant or nursing female subjects. For female subjects, a positive serum β-hCG at screening or Day -1; or for female subjects of childbearing potential an unwillingness to agree to one of the methods of contraception listed in the protocol from screening until the completion of follow-up procedures. Hormonal contraceptive methods (e.g. oral contraceptive pill, implant) for female subjects are not permitted. At least a one week interval between screening and first study drug administration will be observed for the pregnancy tests. * For male subjects, an unwillingness to abstain from sexual intercourse with pregnant or lactating women or an unwillingness to use a condom and another form of contraception (e.g., IUD, birth control pills taken by female partner, diaphragm with spermicide) if engaging in sexual intercourse with a woman who could become pregnant until discharge from the study Donation of blood in excess of 500 mL within 56 days prior to dosing * Full ADP- and/or collagen-induced aggregation (greater than and equal to 40%) at all three concentrations of one or both agonists, as assessed on Day -1 * No ADP- or collagen-induced aggregation (\<40%) at the highest concentration of either agonist, as assessed on Day -1