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The purpose of this study is to examine the potential for drug-drug interactions.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Ensitrelvir | Experimental | Participants will receive multiple oral doses of a combined oral contraceptive (COC) (EE and DRSP) once daily for 24 days (Days 1 to 24) (in the fasted state on Days 18 to 24) in the morning. Participants will also receive ensitrelvir high dose on Day 20 and multiple oral doses of ensitrelvir low dose once daily on Days 21 to 24 in the fasted state. |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Ensitrelvir | Drug | Ensitrelvir will be administered per schedule specified in the arm description. |
|
| Measure | Description | Time Frame |
|---|---|---|
| Maximum Plasma Concentration (Cmax) of Ethinyl Estradiol (EE) | Predose and up to 24 hours postdose on Days 19, 20, and 24 | |
| Cmax of Drospirenone (DRSP) | Predose and up to 24 hours postdose on Days 19, 20, and 24 | |
| Time to Reach Cmax (Tmax) of EE | Predose and up to 24 hours postdose on Days 19, 20, and 24 | |
| Tmax of DRSP | Predose and up to 24 hours postdose on Days 19, 20, and 24 | |
| Area Under the Plasma Concentration-time Curve Over the Dosing Interval (AUC0-τ) of EE | Predose and up to 24 hours postdose on Days 19, 20, and 24 | |
| AUC0-τ of DRSP | Predose and up to 24 hours postdose on Days 19, 20, and 24 |
| Measure | Description | Time Frame |
|---|---|---|
| Number of Participants With Adverse Events (AEs) | Day 1 up to Day 32 | |
| Cmax of Ensitrelvir | Predose and up to 24 hours postdose on Days 20 and 24 | |
| Tmax of Ensitrelvir |
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Key Inclusion Criteria:
Body mass index (BMI) within the range of ≥18.5 to ≤30.0 kilograms (kg)/square meter (m^2) at the screening.
A female participant is eligible to participate if she is not pregnant or breastfeeding, and either of the following conditions applies:
Key Exclusion Criteria:
NOTE: Other inclusion and exclusion criteria may apply.
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| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Early Phase Clinical Unit Los Angeles | Glendale | California | 91206 | United States |
| PubMed Identifier | Type | Citation | Retractions |
|---|---|---|---|
| 41915378 | Derived | Shimizu R, Shibata RY, Kubota R, Okuda S, Sonoyama T. Effects of Ensitrelvir on the Pharmacokinetics of Combined Oral Contraceptives (Ethinyl Estradiol/Drospirenone) in Healthy Adult Women: A Phase 1 Fixed-Sequence, Multiple-Dose, Drug-Drug Interaction Study. Clin Drug Investig. 2026 May;46(5):561-570. doi: 10.1007/s40261-026-01541-3. Epub 2026 Mar 31. |
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| ID | Term |
|---|---|
| C000722354 | ensitrelvir |
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| Predose and up to 24 hours postdose on Days 20 and 24 |
| AUC0-τ of Ensitrelvir | Predose and up to 24 hours postdose on Days 20 and 24 |