The purpose of this study is to assess the effect of multiple doses of esomeprazole on the pharmacokinetics of isavuconazole. In addition, safety and tolerability of isavuconazole alone and in combination with esomeprazole will be assessed

Inclusion Criteria:

• The subject has a body weight of at least 50 kg and a body mass index of 18.5 to 32 kg/m2, inclusive
• The subject's 12-lead electrocardiogram (ECG) is normal
• The subject's clinical laboratory test results are within normal limits

Exclusion Criteria:

• The subject has any history or evidence of any clinically significant cardiovascular, gastrointestinal, endocrinologic, hematologic, hepatic, immunologic, metabolic, urologic, pulmonary, neurologic, dermatologic, psychiatric, renal, and/or other major disease or malignancy
• The subject has a history of bowel obstruction, swallowing disorder, severe gastro-intestinal disorders, major gastrointestinal surgery, gastric/duodenal ulcers or any other condition that may interfere with study drug absorption
• Female subject has been pregnant within 6 months before screening or breast feeding within 3 months before screening
• The subject has a history of unexplained syncope, cardiac arrest, unexplained cardiac arrhythmia or torsade de pointes, structural heart disease, or family history of either Short or Long QT syndrome (suggested by sudden death of a close relative at a young age due to possible or probable cardiac causes). QT is the time between the start of the Q wave and the end of the T wave in the heart's electrical system
• The subject has/had febrile illness or symptomatic, viral, bacterial (including upper respiratory infection), or fungal (non-cutaneous) infection within 1 week prior to clinic admission
• The subject has received a vaccination within the last 30 days prior to study drug administration
• The subject has a positive serology test for Hepatitis B surface antigen (HBsAg), Hepatitis A Immunoglobulin M antibody (anti HAV (IgM)), Hepatitis C antibody (anti-HCV), or human immunodeficiency virus (anti-HIV 1+2)
• The subject has a known or suspected allergy to any of the components of the trial products or the azole class of compounds, or a history of multiple and/or severe allergies to drugs or foods, or a history of severe anaphylactic reactions
• The subject has used tobacco or nicotine containing products in the last 6 months
• The subject has had treatment with any prescribed or non-prescribed drugs (including vitamins, natural and herbal remedies, e.g. St. John's wort) in the 2 weeks prior with the exception of hormonal methods of contraception, hormone replacement therapy, or occasional use of acetaminophen up to 2 g/day
• The subject has participated in any interventional clinical study or has received any investigational drugs within past 30 days or 5 half-lives, whichever is longer
• The subject has had any significant blood loss, donated one unit (450 mL) of blood or more, or received a transfusion of any blood or blood products within 60 days or donated plasma within 7 days prior to clinic admission
• The subject anticipates an inability to abstain from alcohol or caffeine use for 48 hours prior and throughout the duration of the study; or from grapefruit, grapefruit juice, star fruit, or Seville oranges or any products containing these items from 72 hours prior and throughout the duration of the study
• The subject has history of consuming more than 14 units of alcoholic beverages per week within 6 months prior to screening or has a history of alcoholism or drug/chemical/substance abuse within past 2 years prior to screening (Note: one unit = 12 ounces of beer, 4 ounces of wine or 1 ounce of spirits/hard liquor) or the subject tests positive for alcohol or drugs of abuse (amphetamines, barbiturates, benzodiazepines, cannabinoids, cocaine, and opiates)
• The subject has taken part in strenuous exercise within 3 days before Day 1