Recent Updates
Recently added Catalysts

PF-07321332

Phase 3

COVID-19 | Small molecule | Infectious Disease |Pfizer, Inc.|Last Updated: Jul 17, 2025

Target and mechanism

ModalitySmall molecule

Also known as nirmatrelvir

Success Probability

Subscribe to view

Market & Valuation

Subscribe to view

Trial Design

RandomizedDouble-BlindPLACEBO_CONTROLLEDDMC
Total Trials5
Total Enrollment5,799

FDA Designations

No designations recorded

Clinical trial landscape

PF-07321332 · 6 trials · 2 indications

Phase 3 1Phase 2 4Phase 1 1
NCT05261139EPIC-Peds: A Study to Learn About the Study Medicine Called PF-07321332 (Nirmatrelvir)/Ritonavir in Patients Under 18 Years of Age With COVID-19 That Are Not Hospitalized But Are at Risk for Severe DiseaseCOVID-19
RECRUITING160 Analytics
PHASE3RECRUITING
EPIC-Peds: A Study to Learn About the Study Medicine Called PF-07321332 (Nirmatrelvir)/Ritonavir in Patients Under 18 Years of Age With COVID-19 That Are Not Hospitalized But Are at Risk for Severe Disease
COVID-19Unlock trial analytics

Study Endpoints

Primary Endpoints

Cohort 1-2: Maximum Observed Plasma Concentration (Cmax) of nirmatrelvir and ritonavir
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
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.
From Baseline up through Day 34
Incidence of Serious Adverse Events (SAEs) leading to discontinuations.
From Baseline up through Day 34
Incidence of Adverse Events (AEs) leading to discontinuations.
From Baseline up through Day 34
Number of participants with change from Baseline in Vital Signs
From Baseline up through Day 34
Change From Baseline to Day 5 in Viral Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Ribonucleic Acid (RNA) Level in Nasopharyngeal (NP) Swabs: mITT Population
Baseline, Day 5

Baseline was defined as the latest measurement between Day -1 and Day 1, but post-dose samples that were collected within 1 hour post start of dosing were also treated as baseline. Samples with result "\< lower limit of quantification (LLOQ)" were imputed as 1.7 log10 copies/milliliter (mL), and samples with result "Not Detected" were imputed as 0.0 log10 copies/mL.

Percentage of Participants With Sustained Nasopharyngeal (NP) Swab Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Ribonucleic Acid (RNA) < Lower Limit of Quantitation (LLOQ) From Day 15 to Day 44
From Day 15 to Day 44

NP swab was collected by healthcare professional (HCP) from participants and were sent to the central laboratory for viral RNA level testing real-time reverse transcriptase-polymerase chain reaction(RT-PCR). Sustained was defined as NP swab SARS-CoV-2 RNA level not \>=2.0 log10 per milliliter (copies/mL) at any study visit (through Day 44) following the first study visit where the participant's NP swab SARS-CoV-2 RNA level \<LLOQ (\<2.0 log10 copies/mL).

Percentage of Participants Who Developed Symptomatic RT-PCR or RAT Confirmed SARS-CoV-2 Infection Through Day 14: Among Participants With Negative RT-PCR at Baseline
From Day 1 to Day 14

Percentage of participants who developed symptomatic Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) or Rapid Antigen Test (RAT) confirmed SARS-Cov-2 infection were reported in this outcome measure. Index case was defined as participants with symptomatic COVID-19.

Percentage of Participants With Covid-19 Related Hospitalization or Death From Any Cause Through Day 28- Modified Intent-To-Treat (mITT) Population
From Day 1 to Day 28

Percentage of participants with COVID-19 related hospitalization or death from any cause during the first 28 days of the study was estimated using the Kaplan-Meier (KM) method. Using KM method, survival probability for each time interval was calculated as the number of participants surviving divided by the number of participants at risk. Participants who had the event, dropped out, or moved out were not counted as "at risk" i.e., participants who were lost were considered "censored" and were not counted in the denominator.

Maximum Observed Plasma Concentration (Cmax) of Plasma PF-07321332
Day 1 at 0 (pre-dose for PF-07321332), 0.5, 1, 2, 3, 4, 6, 8, 10, and 12 hours, Day 2 at 24 and 36 hours, and Day 3 at 48 hours

Cmax was the maximum observed plasma concentration and was directly observed from data. Concentration values below the lower limit of quantification (LLQ) were set to zero. Geometric mean analysis was on the log scale. Zero values were not included in geometric mean and geometric coefficient of variation calculation. The geometric coefficient of variation was expressed in percentage.

Area Under the Plasma Concentration-Time Profile From Time Zero to Time of the Last Quantifiable Concentration (AUClast) of Plasma PF-07321332
Day 1 at 0 (pre-dose for PF-07321332), 0.5, 1, 2, 3, 4, 6, 8, 10, and 12 hours, Day 2 at 24 and 36 hours, and Day 3 at 48 hours

AUClast was area under the plasma concentration time-curve from zero (pre-dose) to the last measured concentration. The geometric coefficient of variation was expressed in percentage.

Area Under the Plasma Concentration-Time Profile From Time Zero Extrapolated to Infinite Time (AUCinf) of Plasma PF-07321332
Day 1 at 0 (pre-dose for PF-07321332), 0.5, 1, 2, 3, 4, 6, 8, 10, and 12 hours, Day 2 at 24 and 36 hours, and Day 3 at 48 hours

AUCinf was defined as area under the plasma concentration-time curve from time zero to infinity. The geometric coefficient of variation was expressed in percentage.

Secondary Endpoints

Viral load assessment titers measured via reverse transcription polymerase chain reaction (RT-PCR) in nasopharyngeal or nasal swabs over time
Baseline, Day 5, 6, 10, 14 and 28
Proportion of participants with COVID-19 related hospitalization or death from any cause
From Baseline through Day 28
Patient assessment on acceptability and palatability of nirmatrelvir/ritonavir (film-coated tablets and oral powder)
At baseline only for tablets and after each dose for powder formulation
Unlock Study Endpoints

Study Design & Arms

AllocationNON_RANDOMIZED
MaskingNONE
ModelSINGLE_GROUP
PurposeTREATMENT

Treatment Arms

ArmTypeDescription
Cohort 1 nirmatrelvir/ritonavirEXPERIMENTALnirmatrelvir/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
Cohort 2 nirmatrelvir/ritonavirEXPERIMENTALnirmatrelvir/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
Cohort 3 nirmatrelvir/ritonavirEXPERIMENTALnirmatrelvir/ritonavir ≥2 to \<6 years
Cohort 4 nirmatrelvir/ritonavirEXPERIMENTALnirmatrelvir/ritonavir ≥1 month (≥28 days) to \<2 years
Cohort 5 nirmatrelvir/ritonavirEXPERIMENTALnirmatrelvir/ritonavir \<1 month (\<28 days) old
nirmatrelvir plus ritonavir for 5 daysEXPERIMENTALNirmatrelvir (2 tablets) plus ritonavir (1 capsule) will be given by mouth every 12 hours for 5 days
placebo plus ritonavir for 5 daysOTHERplacebo (2 tablets) plus ritonavir (1 capsule) will be given by mouth every 12 hours for 5 days
Nirmatrelvir plus ritonavir for 10 daysEXPERIMENTALNirmatrelvir (2 tablets) plus ritonavir (1 capsule) will be given by mouth every 12 hours for 10 days followed by placebo for nirmatrelvir (2 tablets) plus placebo for ritonavir (1 capsule) every 12 hours for 5 days
Nirmatrelvir plus ritonavir for 15 daysEXPERIMENTALNirmatrelvir (2 tablets) plus ritonavir (1 capsule) will be given by mouth every 12 hours for 15 days.
PF-07321332/ritonavir (5 days)EXPERIMENTALParticipants will receive PF-07321332/ritonavir every 12 hours from Day 1 through Day 5 followed by Placebo every 12 hours from Day 6 through Day 10
PF-07321332/ritonavir (10-Day)EXPERIMENTALParticipants will receive PF-07321332/ritonavir every 12 hours from Day 1 through Day 10.
PlaceboPLACEBO_COMPARATORParticipants will receive placebo every 12 hours from Day 1 through Day 10.
PF-07321332/ritonavirEXPERIMENTALOrally administered PF-07321332+ritonavir
Cohort 1EXPERIMENTALHealthy Volunteer
Cohort 2EXPERIMENTALHepatic Impairment

Interventions

NameTypeDescription
nirmatrelvirDRUGPF-07321332
ritonavirDRUGritonavir
placebo for nirmatrelvirDRUGParticipants will receive 2 tablets of placebo for nirmatrelvir every 12 hours. A placebo does not have any medicine in it but looks just like the medicine being studied.
Placebo for ritonavirDRUGParticipants will receive 1 capsule of placebo for ritonavir every 12 hours. A placebo does not have any medicine in it but looks just like the medicine being studied.
PF-07321332DRUGPF-07321332
Placebo for PF-07321332DRUGPlacebo
PlaceboDRUGPlacebo (tablet or capsule)
Unlock Study Design Details

Eligibility Criteria

Age Range0 Years to 17 Years
SexALL
Healthy VolunteersNo
Study Sites73

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 si...

Countries:United StatesBulgariaJapanMexicoPuerto RicoSouth AfricaUnited KingdomCanadaGreeceItalyTaiwanAustraliaBrazilHungarySlovakiaSpainArgentinaColombiaCzechiaMalaysiaPolandRussiaThailandTurkey (Türkiye)UkraineIndiaSouth Korea
Unlock Eligibility Criteria

Frequently asked questions about PF-07321332

What is Nirmatrelvir/ritonavir used for?

Nirmatrelvir/ritonavir is an investigational small molecule being studied for COVID-19, hepatic impairment, and bioavailability in healthy participants. It is developed by Pfizer, Inc. (PFE) and is currently in Phase 1 clinical development.

Who makes Nirmatrelvir/ritonavir?

Nirmatrelvir/ritonavir is developed by Pfizer, Inc., which trades under the ticker PFE. The drug is in Phase 1 clinical development for conditions including COVID-19 and hepatic impairment.

What phase is Nirmatrelvir/ritonavir in?

Nirmatrelvir/ritonavir is in Phase 1 clinical development. It is an investigational drug and has not been approved by the FDA. Clinical trials are ongoing or completed to evaluate its safety and effects.

What clinical trials is Nirmatrelvir/ritonavir in?

Nirmatrelvir/ritonavir has been studied in several Phase 1 trials, including NCT04962022, NCT04962230, NCT05064800, and NCT05441215. These trials assess drug-drug interactions and effects in healthy participants, including lactating women.

Is Nirmatrelvir/ritonavir the same as nirmatrelvir?

Yes, nirmatrelvir/ritonavir is also known as nirmatrelvir. The drug is a combination product that includes nirmatrelvir and ritonavir, and it is being developed by Pfizer, Inc. for COVID-19 and other conditions.