Suzetrigine for Opioid-Free Recovery After Cesarean Delivery (SPARE)

April 14, 2026 updated by: Lorie Harper, University of Texas at Austin

Suzetrigine Versus Placebo for Opioid-Free Recovery After Cesarean Delivery: A Randomized Controlled Trial

The goal of this clinical trial is to determine whether suzetrigine increases the proportion of patients who remain completely opioid-free from completion of surgery through 72 hours after cesarean delivery.

The main question it aims to answer is:

Does adjunctive suzetrigine, when added to a standardized multimodal postoperative analgesic regimen, increase the proportion of patients who remain opioid-free during the first 72 hours after cesarean delivery?

Researchers will compare suzetrigine to a placebo (a look-alike substance that contains no drug) to evaluate this outcome.

Participants will:

  • Receive either suzetrigine or placebo after cesarean delivery
  • Receive standard postoperative pain management, including acetaminophen, nonsteroidal anti-inflammatory drugs, and neuraxial morphine
  • Have opioid medications available as needed for breakthrough pain
  • Be followed during hospitalization and after discharge to assess pain, recovery, and medication use

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

This is a single-site, randomized, double-blind, placebo-controlled clinical trial evaluating whether adjunctive suzetrigine increases the proportion of patients who remain opioid-free following cesarean delivery. The study is conducted at a tertiary care academic medical center.

Participants undergoing cesarean delivery under neuraxial anesthesia are randomized in a 1:1 ratio to receive either oral suzetrigine or a matching placebo following surgery. Randomization is performed using a computer-generated sequence with permuted blocks of variable size and allocation concealment through a secure electronic system. Participants, clinicians, investigators, and study personnel are blinded to treatment assignment.

The intervention consists of oral suzetrigine administered in the immediate postoperative period, beginning with a loading dose within 90 minutes after skin closure, followed by scheduled maintenance dosing every 12 hours. Participants randomized to the control arm receive a matching placebo on the same schedule. Study medication is prepared and dispensed by the investigational pharmacy in identical packaging to maintain blinding.

All participants receive standardized multimodal postoperative analgesia consistent with institutional enhanced recovery pathways, including scheduled acetaminophen and non-steroidal anti-inflammatory drugs, as well as neuraxial morphine administered intraoperatively. Opioid medications remain available for breakthrough pain at the discretion of the clinical care team.

Suzetrigine is a selective NaV1.8 voltage-gated sodium channel inhibitor that targets peripheral nociceptive pathways and does not act on opioid receptors. This study evaluates its use as an adjunct to standard multimodal analgesia in a postpartum surgical population in which opioid exposure remains common despite guideline-recommended care.

Participants are followed during their inpatient hospitalization and through the early postpartum period using a combination of electronic medical record data and structured follow-up assessments to capture medication use, recovery, and patient-reported outcomes. Data are recorded using secure electronic data capture systems with predefined data fields and standardized collection procedures.

Analyses will be conducted using an intention-to-treat approach, with comparisons between randomized groups based on pre-specified analytical methods appropriate for outcome type.

Participant safety is monitored throughout the study period through routine clinical care, structured follow-up assessments, and oversight by an independent data safety monitoring board.

Study Type

Interventional

Enrollment (Estimated)

90

Phase

  • Phase 4

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • United States
    • Texas
      • Austin, Texas, United States, 78705
        • University of Texas at Austin Dell Medical School, Department of Women's Health
        • Contact:
        • Principal Investigator:
          • Lorie M Harper, MD, MSCI
        • Sub-Investigator:
          • Chase Calvert, MD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Women aged ≥18 years.
  • Undergoing scheduled or unscheduled cesarean delivery during the current admission, with or without concomitant salpingectomy.
  • Planned delivery under neuraxial anesthesia (spinal, epidural, or combined spinal-epidural).
  • Planned Pfannenstiel skin incision.
  • Able to provide informed consent in English or Spanish.
  • Willing and able to complete required remote follow-up assessments through postoperative day 14 (POD14).

Exclusion Criteria:

  • Planned provision of breast milk to the neonate during the period of suzetrigine exposure (while the study drug is being taken and for 96 hours after last dose), due to the absence of human lactation safety data for suzetrigine.*
  • Known allergy, hypersensitivity, or contraindication to suzetrigine or any component of its formulation.
  • Chronic opioid use, defined as daily opioid use for more than 7 consecutive days in the month prior to delivery, or current treatment for opioid use disorder.
  • Significant hepatic disease, defined as AST or ALT >3 times the upper limit of normal or Child-Pugh class B or C.
  • Severe renal impairment, defined as estimated glomerular filtration rate (eGFR) <15 mL/min.

  • Concurrent use of medications known to significantly alter suzetrigine metabolism, including strong CYP3A inhibitors or inducers, such as:

    • ketoconazole
    • ritonavir
    • carbamazepine
    • rifampin
    • St. John's wort (or other agents deemed clinically significant CYP3A modulators by the study investigator team)
  • Planned cesarean delivery under general anesthesia without neuraxial anesthesia.
  • Planned non-Pfannenstiel skin incision (e.g., vertical midline incision).
  • Participation in another interventional pain-management clinical trial during the current hospitalization.
  • Additional operative procedures (excluding salpingectomy) performed at the time of cesarean delivery (e.g., hysterectomy, hernia repair).
  • Inability to provide informed consent or to complete required study procedures and follow-up.

  • Receipt of opioid or sedating medications prior to completion of the informed consent process.

    • Feeding decisions are made independently of study participation. The study does not require participants to alter infant feeding plans; eligibility is determined solely by whether breast milk will be provided to the neonate during the period of study drug exposure (while the study drug is being taken and for 96 hours after last dose). Participants who plan to breastfeed but independently elect not to provide breast milk to the neonate during the period of suzetrigine exposure are eligible.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Suzetrigine
Participants will receive oral suzetrigine following cesarean delivery in addition to standardized multimodal postoperative analgesia, including scheduled acetaminophen and nonsteroidal anti-inflammatory drugs, with opioid medications available as needed for breakthrough pain.
Drug: Suzetrigine
Oral suzetrigine administered following cesarean delivery as an adjunct to standardized multimodal postoperative analgesia, including scheduled acetaminophen and nonsteroidal anti-inflammatory drugs, with opioid medications available as needed for breakthrough pain.
Experimental: Placebo
Participants will receive matching oral placebo following cesarean delivery in addition to standardized multimodal postoperative analgesia, including scheduled acetaminophen and nonsteroidal anti-inflammatory drugs, with opioid medications available as needed for breakthrough pain.
Drug: Placebo
Matching oral placebo administered following cesarean delivery in addition to standardized multimodal postoperative analgesia, including scheduled acetaminophen and nonsteroidal anti-inflammatory drugs, with opioid medications available as needed for breakthrough pain.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Proportion of Participants Remaining Opioid-Free Through 72 Hours Postoperatively
Time Frame: From completion of surgery to 72 hours postoperatively
Proportion of participants who do not receive any opioid medications from completion of cesarean delivery through 72 hours postoperatively.
From completion of surgery to 72 hours postoperatively

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Postoperative Pain Intensity Scores
Time Frame: During hospitalization through 72 hours postoperatively
Patient-reported pain intensity measured using the Numeric Rating Scale (NRS) for pain, an 11-point scale ranging from 0 to 10, where 0 indicates no pain and 10 indicates the worst possible pain. Higher scores represent greater pain intensity.
During hospitalization through 72 hours postoperatively
Maternal Satisfaction With Pain Management
Time Frame: At hospital discharge and postoperative day 14
Participant-reported satisfaction with postoperative pain management assessed using a single-item Likert-type scale ranging from 0 to 10, where 0 indicates completely dissatisfied and 10 indicates completely satisfied. Higher scores indicate greater satisfaction.
At hospital discharge and postoperative day 14
Functional Recovery After Cesarean Delivery
Time Frame: Postoperative day 7
Functional recovery assessed using the Obstetric Quality of Recovery-11 (ObsQoR-11) questionnaire, a validated 11-item patient-reported outcome measure evaluating multiple domains of postoperative recovery, including pain, physical comfort, functional independence, and ability to care for the newborn. Each item is scored on an 11-point numeric scale (0-10), with total scores ranging from 0 to 110. Higher scores indicate better overall recovery.
Postoperative day 7
Post-Discharge Opioid Use
Time Frame: From hospital discharge through postoperative day 14
Participant-reported opioid use after hospital discharge, including total quantity of opioid medications used, collected via structured self-report and expressed as number of tablets consumed or morphine milligram equivalents (MME) when available.
From hospital discharge through postoperative day 14
Study Drug Adherence (Proportion of Prescribed Study Medication Doses Taken)
Time Frame: During hospitalization through postoperative day 7

Participant adherence to the assigned study medication regimen (suzetrigine or matching placebo), defined as the proportion of prescribed study medication doses taken during the postoperative period. Adherence will be calculated as the number of doses taken divided by the number of doses prescribed.

For inpatient doses, adherence will be assessed using the electronic medication administration record (MAR). For postdischarge doses, adherence will be assessed using participant self-report with pill count verification when feasible.
During hospitalization through postoperative day 7
Adverse Events
Time Frame: From study drug initiation through postoperative day 14
Occurrence of adverse events during the study period, assessed through clinical evaluation, electronic medical record review, and participant-reported follow-up assessments.
From study drug initiation through postoperative day 14

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of Texas at Austin

Investigators

  • Study Director: Lorie M. Harper, MD, MSCI, Dell Medical School, University of Texas at Austin, Department of Women's Health

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

June 1, 2026

Primary Completion (Estimated)

February 1, 2028

Study Completion (Estimated)

May 1, 2028

Study Registration Dates

First Submitted

April 7, 2026

First Submitted That Met QC Criteria

April 14, 2026

First Posted (Actual)

April 16, 2026

Study Record Updates

Last Update Posted (Actual)

April 16, 2026

Last Update Submitted That Met QC Criteria

April 14, 2026

Last Verified

April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • STUDY00008784

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

Yes

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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