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CompletedNCT06391177Updated Mar 25, 2025Results posted

A Study to Evaluate Vonoprazan Concentrations in Breast Milk of Healthy Lactating Women Receiving Vonoprazan 20 mg Once Daily or Vonoprazan 20 mg Twice Daily

A Phase 1 interventional study of Vonoprazan in Erosive Esophagitis, Heartburn and Symptomatic Nonerosive Gasroesophageal Reflux Disease, sponsored by Phathom Pharmaceuticals, Inc.. Completed at 1 site in United States. Open to female participants aged 18 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2025-03-25.

Sponsored by Phathom Pharmaceuticals, Inc. · Phase 1, Interventional, and Basic science

Phase
Phase 1
Study type
Interventional
Enrollment
15
Allocation
Non-randomized
Ages
18 Years and older
Sex
Female
01

Study summary

The primary objective is to determine the pharmacokinetics (PK) of vonoprazan in breast milk of healthy lactating women who have received vonoprazan administered once daily or vonoprazan 20 mg administered twice daily for 4 consecutive days.

02

Conditions studied

  • Erosive Esophagitis
  • Heartburn
  • Symptomatic Nonerosive Gasroesophageal Reflux Disease
  • Helicobacter Pylori Infection

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Keywords

  • Healthy participants
  • Helicobacter pylori infection
  • Erosive Esophagitis
  • Symptomatic nonerosive gasroesophageal reflux disease
  • Heartburn
  • Breast milk
  • Lactating women
03

In context

Heartburn

154 studies on the registry are indexed under Heartburn; 12 are open to participants now.

This study's enrollment of 15 is below the median of 100 across 127 interventional studies indexed under Heartburn.

Browse Heartburn studies →

Lead sponsor

Phathom Pharmaceuticals, Inc. is the lead sponsor of 15 studies on the registry; 2 are open to participants now.

Of its 11 completed or terminated interventional studies of FDA-regulated products, 11 (100%) have results posted.

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
18 Years and older
Sexes eligible
Female
Accepts healthy volunteers
Yes

Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.

Inclusion criteria

  1. The participant is a healthy lactating woman at least 18 years of age at the time of signing the form (ICF).
  2. The participant has delivered a normal term infant (at least 37 weeks gestation) and has been breastfeeding or actively pumping breast milk for at least 4 weeks postpartum prior to the first dose.
  3. The participant is willing to not breastfeed or otherwise use her breast milk during administration of vonoprazan and until at least 5 days after the last dose of the study drug.
  4. The participant has confirmed that her breastfed infant is able to feed from a bottle.
  5. The participant agrees to collect all breast milk from pre-dose to 24 hours after the morning dose administration on Day 4, using an electric pump.
  6. The participant is considered by the investigator to be in good general health as determined by medical history, clinical laboratory test results, vital sign measurements, 12-lead results, and physical examination findings at Screening.
  7. Participants of must use an acceptable method of (ie, diaphragm with spermicide, intrauterine device, condom with foam or vaginal spermicide, oral contraceptives, or abstinence) or be surgically sterile (ie, hysterectomy, bilateral tubal ligation, or bilateral oophorectomy). All participants must have a negative pregnancy test at Screening and before the first dose of study drug (Baseline).
  8. The participant agrees to comply with all protocol requirements.
  9. The participant is able to provide written informed consent.

Exclusion criteria

Exclusion Criteria:

  1. The participant has a positive pregnancy test at Screening or Baseline, is planning to become pregnant before, during, or within 4 weeks after participating in this study, or intends to donate ova during this time period, or is of and not using an effective method.
  2. The participant has a history of breast implants, breast augmentation, or breast reduction surgery that significantly impacts breastfeeding or collection of milk from one or both breasts.
  3. The participant has signs or symptoms of mastitis or other condition that would prevent the collection of milk from one or both breasts.
  4. The participant has undergone prior esophageal and/or gastrointestinal surgeries that may affect study drug absorption.
  5. The participant has undergone surgery (other than cesarean section) within 30 days before the first dose of study drug.
  6. The participant has a positive test result for surface antigen, virus antibody, or types 1 or 2 antibodies at Screening.
  7. The participant has any other findings on physical examination, clinical laboratory abnormalities, or results that preclude participation in the study, as deemed by the investigator.
  8. The participant has used any prescription (excluding hormonal birth control) and/or over-the-counter medications (including cytochrome P450 3A4 inducers), including herbal or nutritional supplements, within 14 days before the first dose of study drug, and/or is expected to require any such medication during the course of the study until end of the Treatment Period. Use of multivitamins and acetaminophen (up to 2 g per day) is permissible.
  9. The participant has consumed grapefruit and/or grapefruit juice, Seville orange, or Seville orange-containing products (eg, marmalade) within 7 days before the first dose of study drug and/or is expected to be unable to abstain through the study.
  10. The participant is a smoker or has used nicotine or nicotine-containing products (eg, snuff, nicotine patch, nicotine chewing gum, mock cigarettes, or inhalers) within 6 months before the first dose of study drug.
  11. The participant has a history of alcohol abuse or drug dependency within 12 months before the first dose of study drug.
  12. The participant has a positive test result for drugs of abuse, alcohol, or cotinine (indicating active current smoking) at Screening, Baseline, or Day 4 (Check-in).
  13. The participant is involved in strenuous activity or contact sports within 24 hours before the first dose of study drug and during the study.
  14. The participant has a history of relevant drug and/or food allergies (ie, any significant food allergy that could preclude a standard diet in the clinical research unit).
  15. The participant has received study drug in another study (including vonoprazan) within 30 days prior to start of the Screening Period.
  16. The participant has a history of or allergies to vonoprazan or any of its formulation (D-mannitol, microcrystalline cellulose, hydroxypropyl cellulose, fumaric acid, ascorbic acid, croscarmellose sodium, magnesium stearate, hypromellose, polyethylene glycol 8000, titanium dioxide, or ferric oxide red).
  17. In the opinion of the investigator, the participant is not suitable for entry into the study.
Terms in these criteria, in plain language(11)

Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.

Informed consent

Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.

You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.

ECG (electrocardiogram)

A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.

Childbearing potential

Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).

Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.

Contraception

Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.

Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.

Hepatitis B tests

Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.

Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.

Hepatitis C tests

Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.

After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.

HIV

The human immunodeficiency virus, which weakens the immune system.

Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.

Clinically significant

Judged by the study doctor to matter for your health or for the study. It is a doctor’s decision, so ask the study team if you are unsure whether something counts.

Investigational drug or device

A drug or device being studied in a clinical trial.

It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.

Hypersensitivity

An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.

Excipients

The other ingredients in a medicine besides the active drug, such as fillers, colours or preservatives.

05

Study design

Phase
Phase 1
Primary purpose
Basic science
Allocation
Non-randomized
Intervention model
Parallel assignment
Masking
None (open label)
Enrollment
15 participants (actual)

Study arms

  • Experimental
    Vonoprazan 20 mg Once Daily

    Participants will be administered once-daily doses of vonoprazan 20 mg for 4 consecutive days (Days 1 through 4).

    Drug: Vonoprazan

  • Experimental
    Vonoprazan 20 mg Twice Daily

    Participants will be administered twice-daily doses of vonoprazan 20 mg for 4 consecutive days (Days 1 through 4).

    Drug: Vonoprazan

Interventions

06

What researchers measure

Primary outcomes

  1. Area Under Drug Concentration-time Curve From Time 0 to 24 Hours (AUC0-24) Following the Morning Dose of Vonoprazan in Breast Milk

    AUC from time 0 to 24 hours post-dose, calculated as: the sum of the product of the concentration of the interval and the width of the interval.

    Time frame: Pre-dose on Day 4, and at regularly scheduled intervals through 24 hours after the morning dosing (0-4 hours, 4-8 hours, 8-12 hours, 12-18 hours, and 18-24 hours).

  2. Maximum Drug Concentration (Cmax) of Vonoprazan in Breast Milk

    Maximum observed concentration after dosing.

    Time frame: Pre-dose on Day 4, and at regularly scheduled intervals through 24 hours after the morning dosing (0-4 hours, 4-8 hours, 8-12 hours, 12-18 hours, and 18-24 hours).

  3. Minimum Drug Concentration (Cmin) of Vonoprazan in Breast Milk

    Minimum observed concentration after dosing.

    Time frame: Pre-dose on Day 4, and at regularly scheduled intervals through 24 hours after the morning dosing (0-4 hours, 4-8 hours, 8-12 hours, 12-18 hours, and 18-24 hours).

  4. Average Drug Concentration (Cavg) of Vonoprazan in Breast Milk

    Average concentration, calculated as: AUC0-24/tau (tau=the difference between the end time of the last interval and dosing time).

    Time frame: Pre-dose on Day 4, and at regularly scheduled intervals through 24 hours after the morning dosing (0-4 hours, 4-8 hours, 8-12 hours, 12-18 hours, and 18-24 hours).

  5. Time to Cmax (Tmax) of Vonoprazan in Breast Milk

    Time to maximum observed concentration (actual midpoint of the interval in which Cmax was observed).

    Time frame: Pre-dose on Day 4, and at regularly scheduled intervals through 24 hours after the morning dosing (0-4 hours, 4-8 hours, 8-12 hours, 12-18 hours, and 18-24 hours).

Secondary outcomes

  1. Total Amount of Vonoprazan Excreted in Breast Milk

    Total amount of drug excreted in breast milk over 24 hours; calculated as the sum of drug concentration × expressed milk volume in each collection interval over 24-hour period.

    Time frame: Pre-dose on Day 4, and at regularly scheduled intervals through 24 hours after the morning dosing (0-4 hours, 4-8 hours, 8-12 hours, 12-18 hours, and 18-24 hours).

  2. Percentage of Vonoprazan Excreted in Breast Milk Relative to the Total Dose Received

    Total amount of drug excreted over 24 hours relative to total dose administered; calculated as the sum of (total amount of drug excreted in each collection interval / total dose received over 24-hour period) \* 100.

    Time frame: Pre-dose on Day 4, and at regularly scheduled intervals through 24 hours after the morning dosing (0-4 hours, 4-8 hours, 8-12 hours, 12-18 hours, and 18-24 hours).

  3. Estimated Infant Daily Dose of Vonoprazan

    Estimated weight adjusted daily dose consumed by the infant through breast milk; calculated as total amount of drug excreted over 24-hour period / weight of infant. Calculation used the nominal infant weight of 6.0 kg which is the approximate 50th percentile for a 3-month old infant.

    Time frame: Pre-dose on Day 4, and at regularly scheduled intervals through 24 hours after the morning dosing (0-4 hours, 4-8 hours, 8-12 hours, 12-18 hours, and 18-24 hours).

  4. Estimated Relative Infant Dose to the Total Maternal Dose Received of Vonoprazan

    Percentage of daily infant dose relative to the daily maternal dose; calculated as (daily infant dose / daily maternal dose) \* 100.

    Time frame: Pre-dose on Day 4, and at regularly scheduled intervals through 24 hours after the morning dosing (0-4 hours, 4-8 hours, 8-12 hours, 12-18 hours, and 18-24 hours).

07

Results

Posted Mar 25, 2025

Participant flow

A total of 15 participants were enrolled in the United States between May 2024 and September 2024.

Participant flow — Overall Study
MilestoneVonoprazan 20 mg QDVonoprazan 20 mg BID
Started510
Completed510
Not completed00

Outcome measures

PrimaryArea Under Drug Concentration-time Curve From Time 0 to 24 Hours (AUC0-24) Following the Morning Dose of Vonoprazan in Breast Milk

AUC from time 0 to 24 hours post-dose, calculated as: the sum of the product of the concentration of the interval and the width of the interval.

Time frame:
Pre-dose on Day 4, and at regularly scheduled intervals through 24 hours after the morning dosing (0-4 hours, 4-8 hours, 8-12 hours, 12-18 hours, and 18-24 hours).
Reported as:
Mean · ng•h/mL
Area Under Drug Concentration-time Curve From Time 0 to 24 Hours (AUC0-24) Following the Morning Dose of Vonoprazan in Breast Milk
ng•h/mLVonoprazan 20 mg QDVonoprazan 20 mg BID
Area Under Drug Concentration-time Curve From Time 0 to 24 Hours (AUC0-24) Following the Morning Dose of Vonoprazan in Breast Milk179 ± 61.3317 ± 107
PrimaryMaximum Drug Concentration (Cmax) of Vonoprazan in Breast Milk

Maximum observed concentration after dosing.

Time frame:
Pre-dose on Day 4, and at regularly scheduled intervals through 24 hours after the morning dosing (0-4 hours, 4-8 hours, 8-12 hours, 12-18 hours, and 18-24 hours).
Reported as:
Mean · ng/mL
Maximum Drug Concentration (Cmax) of Vonoprazan in Breast Milk
ng/mLVonoprazan 20 mg QDVonoprazan 20 mg BID
Maximum Drug Concentration (Cmax) of Vonoprazan in Breast Milk20.9 ± 6.0224.7 ± 9.77
PrimaryMinimum Drug Concentration (Cmin) of Vonoprazan in Breast Milk

Minimum observed concentration after dosing.

Time frame:
Pre-dose on Day 4, and at regularly scheduled intervals through 24 hours after the morning dosing (0-4 hours, 4-8 hours, 8-12 hours, 12-18 hours, and 18-24 hours).
Reported as:
Mean · ng/mL
Minimum Drug Concentration (Cmin) of Vonoprazan in Breast Milk
ng/mLVonoprazan 20 mg QDVonoprazan 20 mg BID
Minimum Drug Concentration (Cmin) of Vonoprazan in Breast Milk1.82 ± 0.8336.78 ± 2.19
PrimaryAverage Drug Concentration (Cavg) of Vonoprazan in Breast Milk

Average concentration, calculated as: AUC0-24/tau (tau=the difference between the end time of the last interval and dosing time).

Time frame:
Pre-dose on Day 4, and at regularly scheduled intervals through 24 hours after the morning dosing (0-4 hours, 4-8 hours, 8-12 hours, 12-18 hours, and 18-24 hours).
Reported as:
Mean · ng/mL
Average Drug Concentration (Cavg) of Vonoprazan in Breast Milk
ng/mLVonoprazan 20 mg QDVonoprazan 20 mg BID
Average Drug Concentration (Cavg) of Vonoprazan in Breast Milk7.55 ± 2.5813.3 ± 4.51
PrimaryTime to Cmax (Tmax) of Vonoprazan in Breast Milk

Time to maximum observed concentration (actual midpoint of the interval in which Cmax was observed).

Time frame:
Pre-dose on Day 4, and at regularly scheduled intervals through 24 hours after the morning dosing (0-4 hours, 4-8 hours, 8-12 hours, 12-18 hours, and 18-24 hours).
Reported as:
Median · hours
Time to Cmax (Tmax) of Vonoprazan in Breast Milk
hoursVonoprazan 20 mg QDVonoprazan 20 mg BID
Time to Cmax (Tmax) of Vonoprazan in Breast Milk1.88 (1.83 to 1.93)1.91 (1.88 to 14.8)
SecondaryTotal Amount of Vonoprazan Excreted in Breast Milk

Total amount of drug excreted in breast milk over 24 hours; calculated as the sum of drug concentration × expressed milk volume in each collection interval over 24-hour period.

Time frame:
Pre-dose on Day 4, and at regularly scheduled intervals through 24 hours after the morning dosing (0-4 hours, 4-8 hours, 8-12 hours, 12-18 hours, and 18-24 hours).
Reported as:
Mean · mg
Total Amount of Vonoprazan Excreted in Breast Milk
mgVonoprazan 20 mg QDVonoprazan 20 mg BID
Total Amount of Vonoprazan Excreted in Breast Milk0.00241 ± 0.001180.00904 ± 0.00530
SecondaryPercentage of Vonoprazan Excreted in Breast Milk Relative to the Total Dose Received

Total amount of drug excreted over 24 hours relative to total dose administered; calculated as the sum of (total amount of drug excreted in each collection interval / total dose received over 24-hour period) \* 100.

Time frame:
Pre-dose on Day 4, and at regularly scheduled intervals through 24 hours after the morning dosing (0-4 hours, 4-8 hours, 8-12 hours, 12-18 hours, and 18-24 hours).
Reported as:
Mean · percentage of vonoprazan
Percentage of Vonoprazan Excreted in Breast Milk Relative to the Total Dose Received
percentage of vonoprazanVonoprazan 20 mg QDVonoprazan 20 mg BID
Percentage of Vonoprazan Excreted in Breast Milk Relative to the Total Dose Received0.0120 ± 0.005920.0226 ± 0.0132
SecondaryEstimated Infant Daily Dose of Vonoprazan

Estimated weight adjusted daily dose consumed by the infant through breast milk; calculated as total amount of drug excreted over 24-hour period / weight of infant. Calculation used the nominal infant weight of 6.0 kg which is the approximate 50th percentile for a 3-month old infant.

Time frame:
Pre-dose on Day 4, and at regularly scheduled intervals through 24 hours after the morning dosing (0-4 hours, 4-8 hours, 8-12 hours, 12-18 hours, and 18-24 hours).
Reported as:
Mean · mg/kg/day
Estimated Infant Daily Dose of Vonoprazan
mg/kg/dayVonoprazan 20 mg QDVonoprazan 20 mg BID
Estimated Infant Daily Dose of Vonoprazan0.000401 ± 0.0001970.00151 ± 0.000883
SecondaryEstimated Relative Infant Dose to the Total Maternal Dose Received of Vonoprazan

Percentage of daily infant dose relative to the daily maternal dose; calculated as (daily infant dose / daily maternal dose) \* 100.

Time frame:
Pre-dose on Day 4, and at regularly scheduled intervals through 24 hours after the morning dosing (0-4 hours, 4-8 hours, 8-12 hours, 12-18 hours, and 18-24 hours).
Reported as:
Mean · percentage of total maternal dose
Estimated Relative Infant Dose to the Total Maternal Dose Received of Vonoprazan
percentage of total maternal doseVonoprazan 20 mg QDVonoprazan 20 mg BID
Estimated Relative Infant Dose to the Total Maternal Dose Received of Vonoprazan0.128 ± 0.05560.269 ± 0.186

Adverse events

Collected over Day 1 up to Day 11. Non-serious events are listed at a 0% frequency threshold.

Adverse event summary by group
GroupDeathsSeriousOther
Vonoprazan 20 mg QD0/5 (0%)0/5 (0%)1/5 (20%)
Vonoprazan 20 mg BID0/10 (0%)0/10 (0%)4/10 (40%)
Most frequent other events
Most frequent other events
EventVonoprazan 20 mg QDVonoprazan 20 mg BID
NauseaGastrointestinal disorders1/52/10
HeadacheNervous system disorders0/52/10
Abdominal discomfortGastrointestinal disorders0/51/10
DyspepsiaGastrointestinal disorders0/51/10

Baseline characteristics

Safety population: included all participants who received at least 1 dose of the study drug.

Age, Continuous
Age, Continuous(years)Vonoprazan 20 mg QDVonoprazan 20 mg BIDTotal
Mean34.4 ± 4.4529.7 ± 3.7131.3 ± 4.45
Sex: Female, Male
Sex: Female, Male(Participants)Vonoprazan 20 mg QDVonoprazan 20 mg BIDTotal
Female51015
Male000
Ethnicity (NIH/OMB)
Ethnicity (NIH/OMB)(Participants)Vonoprazan 20 mg QDVonoprazan 20 mg BIDTotal
Hispanic or Latino101
Not Hispanic or Latino41014
Unknown or Not Reported000
Race (NIH/OMB)
Race (NIH/OMB)(Participants)Vonoprazan 20 mg QDVonoprazan 20 mg BIDTotal
American Indian or Alaska Native000
Asian112
Native Hawaiian or Other Pacific Islander000
Black or African American000
White4812
More than one race011
Unknown or Not Reported000
08

Study locations

1 site
  • PPD Development, LP
    Las Vegas, Nevada 89113, United States
09

References and documents

Study documents

PDFs hosted by the registry, ClinicalTrials.gov.

Individual participant data

Plan to share: No

10

Timeline

Tracking since Sep 25, 2026
ElapsedEstimatedEstimated, not yet reached

Ran from May 2024 to primary completion in Sep 2024, 4 months.

Results were first posted in Mar 2025, 6 months after primary completion.

How these figures are worked out, and which studies are left out of them.

Registered
Apr 25, 2024
First posted
Apr 30, 2024
StartActual
May 7, 2024
Primary completionActual
Sep 13, 2024
CompletionActual
Sep 19, 2024
Results first posted
Mar 25, 2025
Last update
Mar 25, 2025
What these dates mean
Start.
When the first participant enrolled; while estimated, when the study expects to open to recruitment.
Primary completion.
When the last participant was examined or treated to collect data for the study's main question, its primary outcome. A study that stopped early gives the date its data collection stopped.
Completion.
When the last participant's last visit took place, for every outcome, secondary ones and side effects included: the end of the study. Often later than primary completion, sometimes the same day.
Actual and Est.
Actual means the registry says the date has happened. Est. (estimated) is a date the sponsor plans or expects. It can still move, and the sponsor is expected to change it to actual once it has passed.
No changes since tracking began. The registry record was last updated on Mar 25, 2025, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗
11

Registry details

Key details

Study ID
NCT06391177
Lead sponsor
Phathom Pharmaceuticals, Inc.
Responsible party
Sponsor
First posted
Apr 30, 2024
Start date
May 7, 2024
Primary completion
Sep 13, 2024
Completion
Sep 19, 2024
Results posted
Mar 25, 2025
Last update
Mar 25, 2025

Oversight

Data monitoring committee
No
FDA-regulated drug
Yes
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

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