A Phase 1 interventional study of prifetrastat Reference and prifetrastat Test 1 in Healthy Participant, sponsored by Pfizer. Recruiting at 1 site in Belgium. Open to participants aged 18 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-07-23.
Sponsored by Pfizer · Phase 1, Interventional, and Basic science
The purpose of this study is to understand the relative amount of drug that enters bloodstream from prifetrastat product lots differing in active ingredient particle size distribution.
The study is seeking participants who are:
Healthy males and females of non-childbearing potential >=18 years of age at screening
Participants in the study will receive a single dose of prifetrastat by mouth. After at least 14 days, they will receive another dose of prifetrastat by mouth. Each dose received by the patient will be in tablet form. The sequence in which tablets are given will be random.
The study will help understand how the difference in particle size distributions of the tablets may, or may not, affect how the drug is absorbed, processed, and eliminated by the body.
Participants will remain in the study clinic for 21 days. However, they may be permitted to leave between periods, and will have one follow-up contact.
Pfizer is the lead sponsor of 3,244 studies on the registry; 139 are open to participants now.
Of its 582 completed or terminated interventional studies of FDA-regulated products, 381 (65%) have results posted.
Counted across the registry records on this site, refreshed daily.
Exclusion
Crossover
Drug: prifetrastat Reference · Drug: prifetrastat Test 1
Crossover
Drug: prifetrastat Reference · Drug: prifetrastat Test 2
Reference Treatment
Test 1 Treatment
Test 2 Treatment
Area under the Plasma Concentration-Time profile from time 0 to extrapolated infinite time (AUCinf) of Reference treatment of prifetrastat (AUClast If data does not permit AUCinf)
AUCinf was area under the plasma concentration time-curve from zero (pre-dose) extrapolated out to infinite time (If data permits).
Time frame: Pre-dose, 0, 0.5, 1, 1.5, 2, 3, 4 ,6 , 8, 12, 24, 36, 48, 72, 96, 144 hours post dose in period 1 and period 2
Maximum Observed Plasma Concentration (Cmax) profile of Reference prifetrastat treatment
Cmax was the maximum observed plasma concentration directly observed from data.
Time frame: Pre-dose, 0, 0.5, 1, 1.5, 2, 3, 4 ,6 , 8, 12, 24, 36, 48, 72, 96, 144 hours post dose in period 1 and period 2
Area under the Plasma Concentration-Time profile from time 0 to extrapolated infinite time (AUCinf) of Test 1 treatment of prifetrastat (AUClast If data does not permit AUCinf)
AUCinf was area under the plasma concentration time-curve from zero (pre-dose) extrapolated out to infinite time (If data permits).
Time frame: Pre-dose, 0, 0.5, 1, 1.5, 2, 3, 4 ,6 , 8, 12, 24, 36, 48, 72, 96, 144 hours post dose in period 1 and period 2
Maximum Observed Plasma Concentration (Cmax) profile of Test 1 prifetrastat treatment
Cmax was the maximum observed plasma concentration directly observed from data.
Time frame: Pre-dose, 0, 0.5, 1, 1.5, 2, 3, 4 ,6 , 8, 12, 24, 36, 48, 72, 96, 144 hours post dose in period 1 and period 2
Area under the Plasma Concentration-Time profile from time 0 to extrapolated infinite time (AUCinf) of Test 2 treatment of prifetrastat (AUClast If data does not permit AUCinf)
AUCinf was area under the plasma concentration time-curve from zero (pre-dose) extrapolated out to infinite time (If data permits).
Time frame: Pre-dose, 0, 0.5, 1, 1.5, 2, 3, 4 ,6 , 8, 12, 24, 36, 48, 72, 96, 144 hours post dose in period 1 and period 2
Maximum Observed Plasma Concentration (Cmax) profile of Test 2 prifetrastat treatment
Cmax was the maximum observed plasma concentration directly observed from data.
Time frame: Pre-dose, 0, 0.5, 1, 1.5, 2, 3, 4 ,6 , 8, 12, 24, 36, 48, 72, 96, 144 hours post dose in period 1 and period 2
Number of Participants With Treatment Emergent Adverse Events (TEAEs)
Time frame: Up to Day 35 after the last dose of study intervention in Period 2
Number of Participants with Clinically Significant Abnormalities in Laboratory Parameters
Time frame: Up to Day 35 after the last dose of study intervention in Period 2
Number of Participants With Clinically Significant Abnormalities in Vital Signs
Time frame: Up to Day 35 after the last dose of study intervention in Period 2
Number of Participants With Clinically Significant Electrocardiogram (ECG) Abnormalities
Time frame: Up to Day 35 after the last dose of study intervention in Period 2
Number of Participants With Clinically Significant Physical Examination Abnormalities
Time frame: Up to Day 35 after the last dose of study intervention in Period 2
Plan to share: No — Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical\_trials/trial\_data\_and\_results/data\_requests.
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.
Pfizer