• Plasma levels of casopitant and ketoconazole will be checked on Day 4 to 9 in Cohort 1. [ Time Frame: Day 4 to 9 in Cohort 1. ]
• Plasma levels of casopitant will be checked on Day 2 to 4 of Period 1 and [ Time Frame: Day 2 to 4 of Period 1 ]
• casopitant and ketoconazole will be checked on Day 4 to 9 of Period 2. [ Time Frame: Day 4 to 9 of Period 2 ]

• Safety is evaluated in Cohort 1 by: - Clinical Lab Tests & Physical Exam at Screen, Day -1 & Followup (FU) [ Time Frame: at Screen, Day -1 & Followup (FU) ]
• - Vitals Signs monitored at Screen, Day -1, 4-7 and FU [ Time Frame: at Screen, Day -1, 4-7 and FU ]
• - 12 lead ECGs at Screen & FU [ Time Frame: at Screen & FU ]
• - Adverse Events Monitoring starting at Day 1 [ Time Frame: Day 1 ]

Casopitant may affect liver enzymes that metabolize ketoconazole. This study is designed to test the safety and the extent of the Casopitant affect on ketoconazole levels in healthy human subjects.

• Drug: Casopitant
• Drug: Ketoconazole

Inclusion criteria:

• A female subject who is non-childbearing potential or using acceptable contraceptive methods.
• Adequate organ system functions.
• Able to swallow and retain oral medication.
• Subject is able to understand and comply with protocol requirements and instruction and is likely to complete the study.

Exclusion Criteria:

• Current clinically relevant abnormality, medical condition, or circumstance that makes the subject unsuitable for the study per the study doctor.
• History of drug or other allergy which, in the opinion of the study doctor, contraindicates participation.
• Use of an investigational drug within 28 days or 5 half-lives.
• Use of prescription or non-prescription drugs, supplements or vitamins (excluding multivitamins) within 14 days, or 5 half-lives prior to first dose of study medication.
• Blood donation in excess of 500mL within 56 days prior to dosing or intends to donate within 30 days of the post-treatment follow-up visit.
• Iron deficiency.
• Positive stool for occult blood.
• Female subject who is pregnant or lactating.
• Male subject who has a history of hypogonadism.
• Positive urine drug screen.
• Positive for HIV antibody, hepatitis C antibody or hepatitis B surface antigen.
• Use of tobacco-containing products within the past 12 months prior to screening.
• History of drug or alcohol abuse or dependence within 6 months of screening.
• History or presence of uncontrolled emesis.
• Presence of active infection.
• History of cholecystectomy or biliary tract disease.
• Active peptic ulcer disease (PUD) or a history of PUD of unknown etiology.
• Any degree of heart failure.
• Consumption of any food or drink containing grapefruit or grapefruit juice, apple juice, Seville oranges, kumquats, pommelos or vegetables from the mustard green family within 7 days prior to the first dose unless prior approval is received.