Evaluation of the Excretion of Suzetrigine Into Breast Milk in Healthy Lactating Female Participants

A Phase 1, Open-label, Single-dose Study Evaluating the Excretion of Suzetrigine Into Breast Milk in Healthy Lactating Female Subjects

The purpose of the study is to evaluate the pharmacokinetics (PK) of suzetrigine (SUZ) and its active metabolite in breast milk of lactating female participants. In addition, the purpose is also to evaluate the relative infant dose (RID), safety and tolerability of SUZ and its active metabolite in lactating female participants.

Study Overview

• Status: Recruiting
• Conditions: Pain
• Intervention / Treatment: Drug: Suzetrigine

Detailed Description

The study is being conducted to evaluate the PK, safety and tolerability of SUZ and its active metabolite in lactating female participants.

This clinical trial information was submitted voluntarily under the applicable law and, therefore, certain submission deadlines may not apply. (That is, clinical trial information for this applicable clinical trial was submitted under section 402(j)(4)(A) of the Public Health Service Act and 42 CFR 11.60 and is not subject to the deadlines established by sections 402(j)(2) and (3) of the Public Health Service Act or 42 CFR 11.24 and 11.44.).

• Study Type: Interventional
• Enrollment (Estimated): 12
• Phase: Phase 1

Contacts and Locations

• Study Contact: Name: Medical Information; Phone Number: 617-341-6777; Email: medicalinfo@vrtx.com

Study Locations

• United States
  • Utah
    • Salt Lake City, Utah, United States, 84124
      • Recruiting
      • ICON - Utah - Salt Lake City Office

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Key Inclusion Criteria:

• Body mass index of greater than or equal to (≥) 18.0 to less than (<) 40.0 kilogram per meter square (Kg/m^2) at the Screening Visit
• Participants between 6 weeks and 12 months (inclusive) postpartum from a pregnancy of at least 37 weeks gestation, as of Day 1
• Willing to perform regular pumping to maintain milk supply for the duration of the study
• Participants with well-established lactation, defined as breastfeeding and/or pumping at least 3 times per day
• Participant agrees to abstain from donating or feeding their infant any breast milk produced after receiving SUZ through the completion of the Safety Follow-up Visit (SFUV)

Key Exclusion Criteria:

• History of febrile illness or other acute illness that has not fully resolved within 14 days before study drug dosing
• History of breast implants, breast augmentation, or breast reduction surgery that significantly impacts breastfeeding or collection of milk from one or both breasts
• History of any illness or any clinical condition that, in the opinion of the investigator, might confound the results of the study or pose an additional risk in administering study drug to the participant
• Pregnant or planning to become pregnant during the study or within 30 days after receiving study drug

Other protocol defined Inclusion/Exclusion criteria may apply.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: SUZ; Participants will receive a single dose of SUZ on Day 1.	Drug: Suzetrigine; Tablets for Oral Administration.; Other Names: VX-548; SUZ; JOURNAVX

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Total Amount of SUZ in Breast Milk of Lactating Female Participants	From Day 1 up to Day 10
Total Amount of SUZ Metabolite in Breast Milk of Lactating Female Participants	From Day 1 up to Day 10

Secondary Outcome Measures

Outcome Measure	Time Frame
Area Under the Concentration Versus Time Curve From the Time of Dosing Extrapolated to Infinity (AUC0-inf) of SUZ and its Metabolite in Breast Milk	From Day 1 up to Day 10
Maximum Observed Concentration (Cmax) of SUZ and its Metabolite in Breast Milk	From Day 1 up to Day 10
RID of SUZ and its Metabolite From Breast Milk	From Day 1 up to Day 10
Safety and Tolerability as Assessed by Number of Participants with Adverse Events (AEs) and Serious Adverse Events (SAEs)	From Day 1 up to Day 16

Collaborators and Investigators

• Sponsor: Vertex Pharmaceuticals Incorporated

Study record dates

Study Major Dates

• Study Start (Actual): February 13, 2026
• Primary Completion (Estimated): February 26, 2027
• Study Completion (Estimated): February 26, 2027

Study Registration Dates

• First Submitted: January 23, 2026
• First Submitted That Met QC Criteria: January 23, 2026
• First Posted (Actual): January 30, 2026

Study Record Updates

• Last Update Posted (Actual): May 13, 2026
• Last Update Submitted That Met QC Criteria: May 8, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Neurologic Manifestations; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Pain
• Other Study ID Numbers: VX25-548-021

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Details on Vertex data sharing criteria and process for requesting access can be found at: https://www.vrtx.com/our-science/clinical-trials-data-sharing/

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No