Drug-drug Interaction Study of Bemnifosbuvir/Ruzasvir (BEM/RZR) and Ethinyl Estradiol/Levonorgestrel (EE/LNG)

April 8, 2026 updated by: Atea Pharmaceuticals, Inc.

A Phase 1, Open-Label Study to Evaluate the Effect of Multiple Oral Doses of Bemnifosbuvir/Ruzasvir Fixed-dose Combination on the Single-Dose Pharmacokinetics of a Combined Oral Contraceptive (Ethinyl Estradiol/ Levonorgestrel) in Healthy Adult Female Participants of Non-Childbearing Potential

Drug-drug interaction study between Ethinyl Estradioll/Levonorgestrel and Bemnifosbuvir/Ruzasvir

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Actual)

24

Phase

  • 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 Locations

  • Canada
    • Montreal
      • Québec, Montreal, Canada
        • Atea Study Site

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

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Healthy post-menopausal or hormonally sterile female
  • Minimum body weight of 50 kg and body mass index (BMI) of 18.0-30 kg/m2.
  • Willing to comply with the study requirements and to provide written informed consent.

Exclusion Criteria:

  • Infected with hepatitis B virus, hepatitis C virus, HIV or SARS-CoV-2.
  • Abuse of alcohol or drugs.
  • Use of other investigational drugs within 28 days of dosing.
  • Concomitant use of prescription medications, or systemic over-the-counter medications.
  • Other clinically significant medical conditions or laboratory abnormalities.

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: Treatment
  • Allocation: Non-Randomized
  • Interventional Model: Sequential Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: EE/LNG
Drug: Ethinyl Estradioll/Levonorgestrel (EE/LNG)
Treatment-A (EE/LNG): A single 0.03 mg/ 0.15 mg dose of EE/LNG (1 × 0.03 mg/ 0.15 mg tablet) will be administered in the morning under fasting conditions on Day 1.
Other Names:
  • Portia® 21
Experimental: BEM/RZR
Drug: Bemnifosbuvir/Ruzasvir (BEM/RZR)
Treatment-B (BEM/RZR): A 550 mg/180 mg dose of BEM/RZR (2 × 275 mg/90 mg BEM/RZR FDC tablets) will be administered once daily (QD) under fasting conditions on Days 8 to 14.
Other Names:
  • BEM (AT-527)/RZR (AT-038)
Experimental: BEM/RZR + EE/LNG
Drug: Bemnifosbuvir/Ruzasvir (BEM/RZR) + Ethinyl Estradioll/Levonorgestrel (EE/LNG)
Treatment-C (BEM/RZR + EE/LNG): BEM (550 mg)/ RZR (180 mg) as 2 × 275 mg/90 mg BEM/RZR FDC tablets will be administered QD in the morning under fasting conditions on Days 15 to 19. A single 0.03 mg/0.15 mg dose of EE/LNG (1 × 0.03 mg/ 0.15 mg tablet) will be concomitantly administered with BEM/RZR on the morning of Day 15.
Other Names:
  • BEM (AT-527)/RZR (AT-038)
  • Portia® 21

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
PK of EE/LNG (Cmax)
Time Frame: Day 1,15
Day 1,15
PK of EE/LNG (AUC)
Time Frame: Day 1,15
Day 1,15

Collaborators and Investigators

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

Sponsor

Atea Pharmaceuticals, Inc.

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)

December 4, 2025

Primary Completion (Actual)

February 17, 2026

Study Completion (Actual)

February 17, 2026

Study Registration Dates

First Submitted

November 19, 2025

First Submitted That Met QC Criteria

November 26, 2025

First Posted (Actual)

December 9, 2025

Study Record Updates

Last Update Posted (Actual)

April 13, 2026

Last Update Submitted That Met QC Criteria

April 8, 2026

Last Verified

November 1, 2025

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • AT-01B-012

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

Yes

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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