This study will consist of a Screening Period, a 7-day Run-in Period, a 12 week double-blind Efficacy Assessment Phase (Treatment Period 1), a double-blind Long-term Extension Phase (Treatment Period 2) of up to 52 weeks, and a Follow-up Visit (7 to 10 days after the End of Treatment (EOT)/Early Termination (ET) Visit).
If patients continue to meet all inclusion and no exclusion criteria at the end of the 7-day Run-in Period, they will be randomized in a 1:1 ratio to receive once daily oral difelikefalin tablets at a dose of 1 mg or placebo for 12 weeks. Subjects will be stratified according to their use or nonuse of medications to treat pruritus prior to randomization as well as the presence or absence of specific medical conditions. During the Long-term Extension Phase, patients will be re-randomized on Day 1 of Treatment Period 2 to receive either oral difelikefalin 1 mg or placebo, once daily for up to an additional 52 weeks. A final safety Follow-up Visit will be conducted 7 to 10 days after the EOT/ET.
Informed consent will be obtained prior to performing any study-specific procedures. Screening will occur within 7 to 28 days prior to randomization to assess eligibility.
