Study to Evaluate the Efficacy and Safety of Oral Difelikefalin for Moderate to Severe Pruritus in Subjects With Notalgia Paresthetica
![]() |
The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Know the risks and potential benefits of clinical studies and talk to your health care provider before participating. Read our disclaimer for details. |
ClinicalTrials.gov Identifier: NCT05978063 |
Recruitment Status :
Recruiting
First Posted : August 7, 2023
Last Update Posted : September 13, 2023
|
- Study Details
- Tabular View
- No Results Posted
- Disclaimer
- How to Read a Study Record
Condition or disease | Intervention/treatment | Phase |
---|---|---|
Pruritus Notalgia Paresthetica | Drug: difelikefalin 2.0 mg tablets Drug: difelikefalin 1.0 mg tablets Drug: difelikefalin 0.25 mg tablets Drug: Placebo tablets | Phase 2 Phase 3 |
Part A of this study will evaluate the benefit-risk of 3 doses of difelikefalin compared to placebo. The dose with the best benefit-risk profile will be further evaluated in Part B. Part A of this study comprises a 28-day Screening Period, a 7-day Run-in Period, an 8-week Double-blind Treatment Period, a 2-week Treatment Discontinuation Period, and a Safety Follow-up Visit (14 days after the last dose of study treatment).
Part B of this study will evaluate the efficacy, safety, and tolerability of oral difelikefalin. The dose of oral difelikefalin to be assessed in Part B will depend on the results of Part A. Part B of this study comprises a 28-day Screening Period, a 7-day Run-in Period, an 8-week Double-blind Treatment Period, up to a 52-week OLE Period, and a Safety Follow-up Visit.
Subjects who participated in Part A of the study may not participate in Part B.
All subjects will sign an informed consent form (ICF) and undergo screening for study eligibility.
Study Type : | Interventional (Clinical Trial) |
Estimated Enrollment : | 440 participants |
Allocation: | Randomized |
Intervention Model: | Parallel Assignment |
Intervention Model Description: | Part A includes 4 arms and Part B includes 2 arms. |
Masking: | Double (Participant, Investigator) |
Primary Purpose: | Treatment |
Official Title: | A 2-part, Multicenter, Randomized, Double-blind Study to Evaluate the Efficacy and Safety of Oral Difelikefalin for Moderate-to-Severe Pruritus in Adult Subjects With Notalgia Paresthetica |
Actual Study Start Date : | August 1, 2023 |
Estimated Primary Completion Date : | March 2026 |
Estimated Study Completion Date : | May 2026 |

Arm | Intervention/treatment |
---|---|
Active Comparator: Difelikefalin 2.0 mg tablets
Oral difelikefalin 2.0 mg tablet administered twice daily
|
Drug: difelikefalin 2.0 mg tablets
Oral difelikefalin 2.0 mg administered twice daily
Other Name: CR845 |
Active Comparator: Difelikefalin 1.0 mg tablets
Oral difelikefalin 1.0 mg tablet administered twice daily
|
Drug: difelikefalin 1.0 mg tablets
Oral difelikefalin 1.0 mg administered twice daily
Other Name: CR845 |
Active Comparator: Difelikefalin 0.25 mg tablets
Oral difelikefalin 0.25 mg tablet administered twice daily
|
Drug: difelikefalin 0.25 mg tablets
Oral difelikefalin 0.25 mg administered twice daily
Other Name: CR845 |
Placebo Comparator: Placebo tablets
Oral placebo tablet administered twice daily
|
Drug: Placebo tablets
Oral Placebo administered twice daily |
- Proportion of subjects achieving ≥4-point improvement from baseline in the weekly mean of the daily 24-hour I-NRS score [ Time Frame: Baseline, Week 8 ]
- Proportion of subjects achieving ≥4-point improvement from baseline in the weekly mean of the daily 24-hour I-NRS score at Week 4 in Part B [ Time Frame: Baseline, Week 4 ]
- Proportion of subjects achieving ≥4-point improvement from baseline in the weekly mean of the daily 24-hour I-NRS score at Week 2 in Part B [ Time Frame: Baseline, Week 2 ]
- Proportion of subjects achieving ≥4-point improvement from baseline in the weekly mean of the daily 24-hour I-NRS score at Week 1 in Part B [ Time Frame: Baseline, Week 1 ]
- Change from Baseline in the Numeric Rating Scale of Burning Sensation and Skin Tingling at Week 8 in Part B [ Time Frame: Baseline, Week 8 ]
- Proportion of Subjects with H-IGA of Clear or Almost Clear at Week 8 in Part B [ Time Frame: Week 8 ]
- Proportion of ≥4-point Improvement in Daily I-NRS at Day 2 in Part B [ Time Frame: Day 2 ]

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.
Ages Eligible for Study: | 18 Years to 80 Years (Adult, Older Adult) |
Sexes Eligible for Study: | All |
Accepts Healthy Volunteers: | No |
Key Inclusion Criteria:
To be eligible for inclusion into the study, a patient must meet the following criteria:
- Subject has clinically confirmed diagnosis of active Notalgia Paresthetica;
- Subject has a history of chronic pruritus due to Notalgia Paresthetica;
- Subject has moderate to severe pruritus;
- Female subject is not pregnant or nursing during any period of the study.
Key Exclusion Criteria:
A patient will be excluded from the study if any of the following criteria are met:
- Subject has pruritus attributed to a cause other than Notalgia Paresthetica;
- Subject has any clinically significant medical condition or physical/laboratory/ECG/vital signs abnormality that would, in the opinion of the investigator, put the subject at undue risk or interfere with interpretation of study results.

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT05978063
Contact: Cara Therapeutics | 203-406-3700 | clinicaltrials.gov@caratherapeutics.com |
United States, Arkansas | |
Cara Therapeutics Study Site | Recruiting |
Hot Springs, Arkansas, United States, 71913 | |
United States, California | |
Cara Therapeutics Study Site | Recruiting |
Los Angeles, California, United States, 90045 | |
United States, Florida | |
Cara Therapeutics Study Site | Recruiting |
Coral Gables, Florida, United States, 33134 | |
United States, Louisiana | |
Cara Therapeutics Study Site | Recruiting |
Metairie, Louisiana, United States, 70006 | |
United States, Texas | |
Cara Therapeutics Study Site | Recruiting |
Houston, Texas, United States, 77056 | |
Cara Therapeutics Study Site | Recruiting |
Pflugerville, Texas, United States, 78660 |
Study Director: | Cara Therapeutics | Cara Therapeutics |
Responsible Party: | Cara Therapeutics, Inc. |
ClinicalTrials.gov Identifier: | NCT05978063 |
Other Study ID Numbers: |
CR845-310601 |
First Posted: | August 7, 2023 Key Record Dates |
Last Update Posted: | September 13, 2023 |
Last Verified: | September 2023 |
Individual Participant Data (IPD) Sharing Statement: | |
Plan to Share IPD: | No |
Studies a U.S. FDA-regulated Drug Product: | Yes |
Studies a U.S. FDA-regulated Device Product: | No |
Notalgia Paresthetica Pruritus CR845 Chronic Itch difelikefalin |
Itch Itching Generalized pruritus NP Neuropathic itch |
Pruritus Back Pain Skin Diseases |
Skin Manifestations Pain Neurologic Manifestations |