A Phase 1 interventional study of PF-08161842 and Placebo for PF-08161842 in Alzheimer Disease, sponsored by Pfizer. Not yet recruiting. Open to participants aged 18 Years to 85 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-10-27.
Sponsored by Pfizer · Phase 1, Interventional, and Basic science
The purpose of this clinical study is to learn about the safety and effects of the study medicine (called PF-08161842) and how it is processed by the body. This is the first time PF-08161842 will be given to people.
This study is seeking healthy adults:
Participants will receive either PF-08161842 tablets or matching placebo tablets. Placebo tablets do not contain active medicine. In some study groups, participants will receive a single dose of study medicine. In other study groups, they will receive the study medicine for 14 days. The tablets will be taken by mouth at the study clinic.
We will compare the experiences of people receiving the study medicine with those of people who do not. This will help researchers determine if PF-08161842 is safe and how it affects the body.
Participants will stay at the study clinic for several days so the study team can closely monitor their health. The study will include physical examinations, checks of blood pressure, heart rate, temperature, and breathing. It will also include blood and urine samples and heart tracing tests (ECGs). Researchers will assess how the body processes the study medicine. Some participants will also have lumbar punctures (spinal taps) to collect small samples of fluid from around the brain and spinal cord. The study team will monitor participants for any reactions throughout the study.
For people receiving a single dose, the study will last for about 9 weeks. For those receiving multiple doses the study will last for about 11 weeks. This includes screening, study visits, clinic stay, and follow-up contact after the last dose.
3,767 studies on the registry are indexed under Alzheimer Disease; 882 are open to participants now.
This study's planned enrollment of 98 is above the median of 68 across 2,862 interventional studies indexed under Alzheimer Disease.
Browse Alzheimer Disease studies →Pfizer is the lead sponsor of 3,326 studies on the registry; 147 are open to participants now.
Of its 598 completed or terminated interventional studies of FDA-regulated products, 391 (65%) have results posted.
Counted across the registry records on this site, refreshed daily.
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.
Exclusion criteria:
Participants will receive PF-08161842 or matching placebo as a single dose on Day 1.
Drug: PF-08161842 · Drug: Placebo for PF-08161842
Participants will receive doses of PF-08161842 or matching placebo from Day 1 through Day 14.
Drug: PF-08161842 · Drug: Placebo for PF-08161842
Oral tablet (Parts A and B).
Matching placebo tablet (Parts A and B).
Number of Participants With Treatment Emergent Adverse Events (TEAEs)
Time frame: From first dose through approximately 28 to 35 days after the last dose
Number of Participants With Serious Adverse Events (SAEs)
Time frame: From first dose through approximately 28 to 35 days after the last dose
Number of Participants With Clinically Significant Laboratory Abnormalities
Time frame: From first dose through approximately 28 to 35 days after the last dose
Number of Participants With Clinically Significant Vital Signs Abnormalities
Time frame: From first dose through approximately 28 to 35 days after the last dose
Number of Participants With Clinically Significant Electrocardiogram (ECG) Findings
Time frame: From first dose through approximately 28 to 35 days after the last dose
Number of Participants With Clinically Significant Columbia-Suicidality Severity Rating Scale (C-SSRS)
Time frame: From first dose through approximately 28 to 35 days after the last dose
Area Under the Concentration-time Curve From Time Zero to the Time of the Last Quantifiable Concentration (AUClast)
Time frame: Part A only: Up to Day 5
Area Under the Curve From Time Zero to end of Dosing Interval (AUCtau)
Time frame: Part B only: Up to Day 17
Maximum Observed Plasma Concentration (Cmax)
Time frame: Part A: Up to Day 5 Part B: Up to Day 17
Time to Reach Maximum Observed Plasma Concentration (Tmax)
Time frame: Part A: Up to Day 5 Part B: Up to Day 17
Area Under the Curve From Time Zero to Extrapolated Infinite Time (AUCinf) if data permit
Time frame: Part A only: Up to Day 5
Plasma Decay Half-life (t1/2) if data permit
Time frame: Part A only: Up to Day 5
Cerebrospinal Fluid (CSF) Concentration of PF-08161842
Time frame: Part A: At day 2 post dose Part B: At day 15 post dose
No study locations are listed for this record.
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.
Start is estimated for Nov 2026; primary completion for Mar 2027, 4 months later.
Of 151 industry-sponsored phase 1 interventional studies under Alzheimer Disease, half reached primary completion within 14 months of starting (the median), counting those still running; a quarter within 6 and three quarters within 26. This study's planned 4 months is below that.
Counting every sponsor, half of 222 studies reached it within 18 months; a quarter within 8 and three quarters within 41.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is not yet recruiting, as verified in Oct 2026. You cannot join it, but the record below documents what was studied.
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