Recruiting
Phase 3

PF-07321332 with Ritonavir

Sponsor:

Pfizer

Code:

NCT05261139

Conditions

COVID-19

Eligibility Criteria

Sex: All

Age: 0 - 17

Healthy Volunteers: Not accepted

Interventions

nirmatrelvir

ritonavir

Study Details

Brief summary:

The purpose of this clinical trial is to learn about the safety, pharmacokinetics (pharmacokinetics helps us understand how the drug is changed and eliminated from your body after you take it), and efficacy (how well a study treatment works in the study) of the study medicine (called nirmatrelvir/ritonavir) for potential treatment of coronavirus disease 2019 (COVID-19).

The study medicine will be given to patients under 18 years of age with COVID-19 that are not hospitalized but are at risk for severe disease.

Conditions

COVID-19

Study ID

NCT05261139

Start date

Mar 7, 2022

Status verified date

Jul, 2025

Completion date

Jul 30, 2026

Anticipated

Primary completion date

Jul 30, 2026

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 0 - 17

Healthy Volunteers: Not accepted

Inclusion criteria:

  • Male and female, age 0 to < 18 years, able to swallow for some participants
  • Confirmed SARS-CoV-2 infection within 72 hours prior to enrollment
  • Initial onset of COVID-19 signs/symptoms within 5 days prior to the day of enrollment and at least 1 of the specified COVID-19 signs/symptoms present at enrollment
  • Has at least 1 characteristic or underlying medical condition associated with an increased risk of developing severe illness from COVID-19

Exclusion Criteria:

  • History of or need for hospitalization for the medical treatment of COVID-19
  • Total bilirubin >=2X upper limit of normal (ULN) (except for Gilbert's syndrome)
  • Receiving dialysis or have known moderate to severe renal impairment
  • Suspected or confirmed concurrent active systemic infection other than COVID-19
  • History of hypersensitivity or other contraindication to any of the components of the study intervention
  • Current or expected use of any medications or substances that are highly dependent on CYP3A4 for clearance or strong inducers of cytochrome P450 (CYP)3A4
  • Has received or is expected to receive antibody treatment, antiviral treatment or convalescent COVID-19 plasma
  • Participating in another interventional clinical study with an investigational compound or device, including those for COVID-19 through the study follow up
  • Females who are pregnant or breastfeeding

Study Design

Enrollment

160 participants

Anticipated

Allocation

Non randomized

Intervention Model

Single group

Primary purpose

Treatment

Interventions and Outcome Measures

Arms

experimental: Cohort 1 nirmatrelvir/ritonavir

nirmatrelvir/ritonavir will be given by tablets or powder by mouth twice a day for 5 days (10 doses total).

Weight ≥40 kg

1. ≥12 to <18 years
2. ≥6 to <12 years

experimental: Cohort 2 nirmatrelvir/ritonavir

nirmatrelvir/ritonavir will be given as powder by mouth twice a day for 5 days (10 doses total) Weight ≥20 to <40 kg, ≥6 to <18 years

experimental: Cohort 3 nirmatrelvir/ritonavir

nirmatrelvir/ritonavir

≥2 to <6 years

experimental: Cohort 4 nirmatrelvir/ritonavir

nirmatrelvir/ritonavir

≥1 month (≥28 days) to <2 years

experimental: Cohort 5 nirmatrelvir/ritonavir

nirmatrelvir/ritonavir <1 month (<28 days) old

Interventions

nirmatrelvir

PF-07321332

ritonavir

ritonavir

Primary outcome measure

  • Cohort 1-2: Maximum Observed Plasma Concentration (Cmax) of nirmatrelvir and ritonavir [ Time Frame: Day 1: 1 hour-post dose; Day 4: pre-dose; Day 5: pre-dose, and 1, and 2 hours post dose ]
  • Cohort 1-2: Area Under the Curve to the End of the Dosing Period (AUC0-tau) of nirmatrelvir and ritonavir [ Time Frame: Day 1: 1 hour-post dose; Day 4: pre-dose; Day 5: pre-dose, and 1, and 2 hours post dose ]
  • Incidence of Treatment Emergent Adverse Events (TEAEs) leading to discontinuations. [ Time Frame: From Baseline up through Day 34 ]
  • Incidence of Serious Adverse Events (SAEs) leading to discontinuations. [ Time Frame: From Baseline up through Day 34 ]
  • Incidence of Adverse Events (AEs) leading to discontinuations. [ Time Frame: From Baseline up through Day 34 ]
  • Number of participants with change from Baseline in Vital Signs [ Time Frame: From Baseline up through Day 34 ]

Central Contacts and Locations

Central contacts

Pfizer CT.gov Call Center

1-800-718-1021ClinicalTrials.gov_Inquiries@pfizer.com

Locations

Life Spring Research Foundation

Recruiting

Miami, Florida, United States, 33130

Children's Healthcare of Atlanta - Arthur M. Blank Hospital

Recruiting

Atlanta, Georgia, United States, 30329

University of Chicago Medical Center

Recruiting

Chicago, Illinois, United States, 60637

Louisiana State University Health Sciences Shreveport

Recruiting

Shreveport, Louisiana, United States, 71101

Consano Clinical Research, LLC

Recruiting

Shavano Park, Texas, United States, 78231

More Information

Sponsor

Pfizer

Last update posted

Jul 17, 2025

Last verified

Jul, 2025

Keywords

  • Severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2)
  • Pediatrics

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-08. This information was provided to ClinicalTrials.gov by Pfizer on 2025-07-17.