Evaluate the Safety, Tolerability, and PK of EP547 in Healthy Subjects and Subjects With Cholestatic or Uremic Pruritus

Inclusion Criteria: Healthy Subjects: * Age 18 to 60 years, inclusive * Body mass index greater than or equal to 19 to less than or equal to 35 kg/m2 * Medically healthy with no clinically significant medical history, physical examination, vital sign, standard 12- lead ECG, chemistry, hematology, urinalysis, or coagulation results at Screening as deemed by the Investigator * Male and female subjects must use adequate birth control and agree not to donate sperm or eggs for the time periods specified in the protocol Subjects with Cholestatic Pruritus: * Age 18 to 80 years, inclusive * Has a cholestatic disorder * Has experienced daily or near-daily moderate to severe pruritus for greater than 4 weeks before Screening and at study entry has itch scores indicative of moderate to severe pruritus * If currently taking medications to treat the cholestatic disorder, must be on a stable dose for greater than 12 weeks before Screening and plans to maintain the regimen throughout the study * If currently taking medications known to impact pruritus, must be on a stable dose for greater than 4 weeks before Screening and plans to maintain the regimen throughout the study * Male and female subjects must use adequate birth control and agree not to donate sperm or eggs for the time periods specified in the protocol Subjects with Uremic Pruritus * Age 18 to 80 years, inclusive * Has ESRD and is receiving hemodialysis 3× per week * Has experienced daily or near-daily moderate to severe pr…