A Study to Learn How Different Forms of the Study Medicine Called Prazosin Are Taken up Into the Blood in Healthy Adults

May 12, 2026 updated by: Pfizer

A 2 COHORT, SINGLE DOSE, OPEN-LABEL, RANDOMIZED, PIVOTAL BIOEQUIVALENCE STUDY TO QUALIFY MANUFACTURING SITE TRANSFER FROM BARCELONETA TO ASCOLI FOR PRAZOSIN HYDROCHLORIDE CAPSULES IN HEALTHY ADULT PARTICIPANTS UNDER FASTED CONDITIONS

Prazosin hydrochloride (HCl) is a medicine taken by mouth that helps lower high blood pressure. It's used to treat hypertension, as well as heart failure. The purpose of this clinical trial is to prove that the prazosin HCl capsules made at the manufacturing site at Barceloneta (Puerto Rico) work the same in the body, as those made at Ascoli (Italy). This will be done by understanding how the different capsules and doses of prazosin HCL are changed and eliminated from your body after you take them. The study will also check how safe these capsules are and how well people can handle them.

This study is seeking participants ≥ 18 years old, who are healthy and have a total body weight >50 kg (110 lb). Before starting, participants will be interviewed and examined by skilled personnel to make sure they qualify. This will happen up to 28 days before the first dose of the study drug. Those who are eligible will check into the clinical research unit (CRU) the day before first dose of the study drug and stay there until 24 hours after their last dose [for approximately 9 days and 8 nights for cohort (group) 1 and 5 days and 4 nights for cohort (group) 2].

While in CRU each participant will receive by mouth either 4 capsules (cohort 1) or 2 capsules (cohort 2) of prazosin HCL at different time points. The capsules will be taken with a glass of water after overnight fasting. No food is allowed until 4 hours after taking the dose. Water is allowed freely except for 1 hour before dosing and can be consumed again 1 hour after dosing. Blood samples will be taken from participants right before they take the medicine and again after they have taken it. Electrocardiogram and blood pressure will be closely monitored.

We will compare the experiences of people receiving capsules manufactured at Barceloneta to those manufactured at Ascoli. This will help us determine if capsules from Barceloneta and Ascoli are safe and effective.

After completing all tests, participants will leave the CRU. Then, about 28 to 35 days after their final dose, they'll receive a follow-up phone call to check on their health.

The total duration of participation from the initial ("screening") visit to discharge from the CRU will be approximately 5 weeks and from the initial visit to follow up phone call will be approximately 10 weeks.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Completed

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
69

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 1

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • Belgium
    • Bruxelles-capitale, Région de
      • Brussels, Bruxelles-capitale, Région de, Belgium, B-1070
        • Pfizer Clinical Research Unit - Brussels

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion:

  • Male and female participants, 18 years of age or older and who are overtly healthy as determined by medical evaluation
  • Willing to comply with all study procedures
  • BMI of 16-32 kg/m2; and a total body weight >50 kg (110 lb)
  • Capable of giving signed informed consent

Exclusion:

  • Evidence or history of clinically significant disease
  • Evidence of any active suicidal ideation in the past year or suicidal behavior in the past 5 years
  • Use of drugs within 14 days or 5 half-lives (whichever is longer) prior to study intervention
  • Previous administration of an investigational product (drug or vaccine) within 30 days or 5 half-lives preceding the first dose of study intervention

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Cohort 1
Participants will receive a single dose of Prazosin HCl in 4 treatments.
Drug: Prazosin HCl
Administered Orally; available in capsule form
Other Names:
  • CP-012299
Experimental: Cohort 2
Participants will receive a single dose of Prazosin HCl in 2 treatments.
Drug: Prazosin HCl
Administered Orally; available in capsule form
Other Names:
  • CP-012299

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Time Frame
Pharmacokinetics: Area under the plasma concentration (AUC) of prazosin
Time Frame: Predose, upto 5 weeks
Predose, upto 5 weeks
PK: Maximum plasma concentration (Cmax) of prazosin
Time Frame: Predose, upto 5 weeks
Predose, upto 5 weeks

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Time Frame
Number of Participants with Treatment Emergent Adverse Events (TEAEs)
Time Frame: Through study completion, approximately 10 weeks
Through study completion, approximately 10 weeks
Number of Participants With Clinical Laboratory Abnormalities
Time Frame: Through study completion, approximately 10 weeks
Through study completion, approximately 10 weeks
Number of participants with change from baseline in physical examinations
Time Frame: Through study completion, approximately 10 weeks
Through study completion, approximately 10 weeks
Number of Participants With Clinically Significant Changes From Baseline in 12-Lead Electrocardiogram (ECG) Parameters
Time Frame: Through study completion, approximately 10 weeks
Through study completion, approximately 10 weeks
Number of Participants With Abnormalities in Vital Signs
Time Frame: Through study completion, approximately 10 weeks
Through study completion, approximately 10 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Pfizer

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Study Director: Pfizer CT.gov Call Center, Pfizer

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

Helpful Links

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
November 14, 2025

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
April 3, 2026

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
April 30, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
November 13, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 13, 2025

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
November 17, 2025

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
May 14, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
May 12, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
May 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • A0281007

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

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.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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