Study to Assess Pharmacokinetic Drug-Drug Interaction Between Avatrombopag When Co-Administered With Fluconazole, Itraconazole, or Rifampin in Healthy Subjects

This study will be a single center, open-label, drug-drug interaction study in healthy participants. The study will consist of 3 parts: In Part A, the effects of steady-state dosing of a moderate inhibitor of CYP2C9 and CYP3A (fluconazole) on the single-dose PK of avatrombopag will be assessed. In Part B, the effects of steady-state dosing of a strong CYP3A inhibitor (itraconazole) on the single-dose PK of avatrombopag will be assessed. In Part C, the effects of steady-state dosing of a strong CYP3A and moderate CYP2C9 inducer (rifampin) on the single-dose PK of avatrombopag will be assessed.

Each Part of the study will consist of 2 phases: Pretreatment and Treatment. The Pretreatment Phase will consist of 2 periods: Screening and Baseline Period 1.The Treatment Phase will consist of 2 treatment periods: Treatment Period 1 (administration of a single oral dose of avatrombopag 20 mg alone under fed conditions); and Treatment Period 2 (administration of oral doses of each inhibitor or inducer alone and concomitant administration of a single oral dose of avatrombopag 20 mg with each inhibitor or inducer [fluconazole in Part A, itraconazole in Part B, or rifampin in Part C] under fed conditions).

Inclusion criteria

• Platelet count between the lower limit of normal and 300 × 10^9/L, inclusive, at Screening and each Baseline.
• Non-smoking, male or female, age ≥18 years and ≤55 years old.
• Body mass index (BMI) >18 and ≤32 kg/m^2 at Screening.
• Females must not be pregnant at Screening as documented by a negative serum beta human chorionic gonadotropin (β-hCG) test with a minimum sensitivity 25 IU/L or equivalent units of β-hCG or at Baseline as documented by a negative urine pregnancy test result.

Exclusion criteria

• Failure to discontinue use of agents associated with higher risk of thrombosis (including estrogen containing oral contraceptives) within at least 30 days before dosing.
• Evidence of organ dysfunction or any clinically significant deviation from normal in their medical history (e.g., history of splenectomy); history of arterial or venous thrombosis, including partial or complete thromboses (e.g., stroke, transient ischemic attack, myocardial infarction, deep vein thrombosis, pulmonary embolism); known family history of hereditary thrombophilic disorders (e.g., Factor V Leiden, antithrombin III deficiency).
• Hemoglobin less than lower limit of normal at Screening and Baseline Period 1.
• Liver functions tests (alanine transaminase [ALT], aspartate transaminase [AST], or total bilirubin) greater than the upper limit of normal Screening and Baseline Period 1.
• Any history of gastrointestinal surgery that may affect the pharmacokinetics (PK) profiles of avatrombopag (e.g., hepatectomy, nephrectomy, cholecystectomy or digestive organ resection) at Screening.