A Study to Learn About the Study Medicine (Nirmatrelvir Plus Ritonavir) in Pregnant Women With COVID-19

NCT05386472 | Terminated Phase 1 DMC FDA Drug

• 2 other identifiers: C4671035NCT05386472
• Study Type: interventional
• Target: 25
• Locations: 1 country
• Sites: 13

Brief Summary

The purpose of this clinical trial is to learn about how study medicine (Paxlovid, which contains nirmatrelvir and ritonavir) is changed and eliminated from the body, as well as its safety, and the extent to which side effects can be tolerated for treatment of pregnant women with mild or moderate COVID-19 compared to non-pregnant women with mild or moderate COVID-19. This study is seeking participants who:

• are expecting a healthy baby and are in their second or third trimester pregnancy and have mild or moderate COVID-19
• are not pregnant and have mild or moderate COVID-19. All participants in this study will take Paxlovid by mouth every 12 hours for 5 days. We will study the experiences of people receiving the study medicine. This will help us decide if the study medicine is safe. All participants will take part in this study for at least 34 days; pregnant participants will take part until their delivery, so that the study duration may be up to 6 months, depending on their delivery date. During this time, participants will have 7to 8 visits and, if pregnant, a visit at delivery. Around 2 to 3 visits and the delivery visit will be done in person (at the clinic or at the participant's home). The other 5 visits may be done over the phone, unless in-person visit is necessary as decided by the doctor. Blood samples will be collected on the first 4 to 5 study visits (and at other study visits, if necessary).

Conditions

COVID-19

Keywords

Severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2); Pregnancy; Paxlovid; Nirmatrelvir

Outcome Measures

Primary Outcomes (8)

• Apparent Oral Clearance (CL/F)

  Day 1: 1-3 hour post-dose; Day 3: 4-8 hour post-dose; Day 4: 8 to less than 12 hour post dose; Day 5: 2-4 hour, 6-8 hour, 10 to less than 12 hour post dose.

• Apparent Volume of Distribution (Vz/F)

  Day 1: 1-3 hour post-dose; Day 3: 4-8 hour post-dose; Day 4: 8 to less than 12 hour post dose; Day 5: 2-4 hour, 6-8 hour, 10 to less than 12 hour post dose.

• Area Under the Curve From Time Zero to End of Dosing Interval (AUCtau)

  Day 1: 1-3 hour post-dose; Day 3: 4-8 hour post-dose; Day 4: 8 to less than 12 hour post dose; Day 5: 2-4 hour, 6-8 hour, 10 to less than 12 hour post dose.

• Maximum Observed Plasma Concentration (Cmax)

  Day 1: 1-3 hour post-dose; Day 3: 4-8 hour post-dose; Day 4: 8 to less than 12 hour post dose; Day 5: 2-4 hour, 6-8 hour, 10 to less than 12 hour post dose.

• Plasma Decay Half-Life (t1/2)

  Day 1: 1-3 hour post-dose; Day 3: 4-8 hour post-dose; Day 4: 8 to less than 12 hour post dose; Day 5: 2-4 hour, 6-8 hour, 10 to less than 12 hour post dose.

• Observed Plasma Trough Concentration (Ctrough)

  Day 1: 1-3 hour post-dose; Day 3: 4-8 hour post-dose; Day 4: 8 to less than 12 hour post dose; Day 5: 2-4 hour, 6-8 hour, 10 to less than 12 hour post dose.

• Incidence of Treatment Emergent Adverse Events (TEAEs)

  Baseline up through Day 34

• Incidence of TEAEs, SAEs, and AEs leading to discontinuations

  Baseline up through end of treatment (Day 5/Day 6)

Secondary Outcomes (19)

• Number of participants with delivery at medical facility

  At delivery of the baby

• Number of participants with delivery at home

  At delivery of the baby

• Number of participants with delivery at other location

  At delivery of the baby

• Number of participants with caesarean section delivery

  At delivery of the baby

• Number of participants with vaginal delivery

  At delivery of the baby

Study Arms (3)

Cohort 1

EXPERIMENTAL

Pregnant women in their second trimester

Drug: nirmatrelvir; Drug: ritonavir

Cohort 2

EXPERIMENTAL

Pregnant women in their third trimester

Drug: nirmatrelvir; Drug: ritonavir

Cohort 3

EXPERIMENTAL

Non-pregnant women

Drug: nirmatrelvir; Drug: ritonavir

Interventions

nirmatrelvir DRUG

Nirmatrelvir (tablets) administered by mouth every 12 hours for 5 days (10 doses total)

Also known as: PF-07321332

Cohort 1; Cohort 2; Cohort 3

ritonavir DRUG

Ritonavir (capsules) administered by mouth every 12 hours for 5 days (10 doses total)

Cohort 1; Cohort 2; Cohort 3

Eligibility Criteria

• Age: 18 Years - 50 Years
• Gender Eligibility Details: Pregnant and non-pregnant females
• Healthy Volunteers: No
• Age Groups: Adult (18-64)

You may qualify if:

• All cohorts: Mild-to-moderate COVID-19 infection confirmed in sample collected ≤5 days prior to enrollment; onset within 5 days prior to enrollment and presence of ≥1 sign/symptom on the day of enrollment.
• Cohorts 1\&2: Expecting single baby; Pregnant in 2nd trimester, 14 0/7 to 27 6/7 weeks of gestational age (Cohort 1) or 3rd trimester, ≥28 0/7 and ≤34 6/7 weeks of gestational age (Cohort 2), by ultrasound.

You may not qualify if:

• All cohorts: Current need for hospitalization or anticipated need for hospitalization in the clinical opinion of the site investigator.
• Cohorts 1\&2: Prior/current major condition or illness of mother/fetus substantially increasing risk of study participation/completion or impacting pregnancy/fetal outcomes in investigator's judgement.
• All cohorts: Current use of any medications that are highly dependent on CYP3A4 for clearance, and which are contraindicated in combination with nirmatrelvir/ritonavir.
• All cohorts: Has received or is expected to receive monoclonal antibody treatment, convalescent COVID-19 plasma, or anti-viral treatment (eg, molnupiravir) for the current SARSCoV-2 infection.
• All cohorts: Participants with moderate to severe kidney impairment

Sponsors & Collaborators

• Pfizer: lead

Study Sites (13)

University of Alabama at Birmingham/Center for Women's Reproductive Health

Birmingham, Alabama, 35233, United States

Location

Beautiful Minds Clinical Research Center

Cutler Bay, Florida, 33157, United States

Location

Omega Research Debary

DeBary, Florida, 32713, United States

Location

Omega Research Orlando

Orlando, Florida, 32808, United States

Location

Santos Research Center

Tampa, Florida, 33615, United States

Location

Clinical Research Prime

Idaho Falls, Idaho, 83404, United States

Location

Boeson Research MSO

Missoula, Montana, 59804, United States

Location

Origin Health

Missoula, Montana, 59804, United States

Location

Maximos Ob/Gyn

League City, Texas, 77573, United States

Location

University of Utah

Salt Lake City, Utah, 84108, United States

Location

University of Utah

Salt Lake City, Utah, 84112, United States

Location

University of Utah Clinical Neuroscience Center

Salt Lake City, Utah, 84132, United States

Location

University of Utah Hospital

Salt Lake City, Utah, 84132, United States

Location

Related Links

• To obtain contact information for a study center near you, click here.

MeSH Terms

Conditions

COVID-19

Interventions

nirmatrelvir; Ritonavir

Condition Hierarchy (Ancestors)

Pneumonia, Viral; Pneumonia; Respiratory Tract Infections; Infections; Virus Diseases; Coronavirus Infections; Coronaviridae Infections; Nidovirales Infections; RNA Virus Infections; Lung Diseases; Respiratory Tract Diseases

Intervention Hierarchy (Ancestors)

Thiazoles; Sulfur Compounds; Organic Chemicals; Azoles; Heterocyclic Compounds, 1-Ring; Heterocyclic Compounds

Study Officials

• Pfizer CT.gov Call Center

  Pfizer

  STUDY DIRECTOR

Study Design

• Study Type: interventional
• Phase: phase 1
• Allocation: NON RANDOMIZED
• Masking: NONE
• Masking Details: (Open Label)
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: May 20, 2022
• First Posted: May 23, 2022
• Study Start: June 22, 2022
• Primary Completion: March 26, 2025
• Study Completion: May 12, 2025
• Last Updated: July 29, 2025

Record last verified: 2025-07

Data Sharing

• IPD Sharing: Will not share

Locations

US (13)