This study will evaluate the potential pharmacokinetic (PK) and pharmacodynamic (PD) interaction between the XO inhibitor febuxostat and the investigational URAT1 inhibitor RDEA3170 and provide information for potential future clinical studies using this combination. Combination treatment using 2 drugs with different mechanisms of action may achieve improved response and may allow the use of lower doses, resulting in fewer side effects than the use of either drug alone.

Inclusion Criteria:

• body weight ≥ 50 kg (110 lbs.) and a body mass index ≥ 18 and ≤ 40 kg/m2.
• no clinically relevant abnormalities in vital signs, ECG, physical examination or safety laboratory values, per the Investigator's judgment.
• a screening serum urate level ≥ 4.5 mg/dL.

Exclusion Criteria:

• history or suspicion of kidney stones.
• history of cardiac abnormalities as assessed during screening, including abnormal and clinically relevant electrocardiogram changes and/or family history of sudden death in otherwise healthy individual between the ages of 1 and 30 years.
• undergone major surgery within 3 months prior to Day 1.
• donated blood or experienced significant blood loss (> 450 mL) within 12 weeks prior to Day 1 or gave a plasma donation within 4 weeks prior to the Screening Period.
• inadequate venous access or unsuitable veins for repeated venipuncture.