Recruiting

Plan B®

Sponsor:

McMaster University

Code:

NCT07759635

Conditions

Female

Premenopausal

Eligibility Criteria

Sex: Female

Age: 18 - 35

Healthy Volunteers: Accepted

Interventions

Plan B (Levonorgestrel)

Placebo (gelatin capsule)

Study Details

Brief summary:

The goal of this double-blind randomized controlled trial is to learn about the impacts of a single dose of Plan B® on the cardiovascular system in young, health, premenopausal females. The main questions it aims to answer are:

1. What is the short-term affect of Plan B® affect on the venous system?
2. What is the short-term affect of Plan B® affect on the health of arteries?

Researchers will compare a single dose of Plan B® (1.5 mg of levonorgestrel) to a placebo to see if Plan B® has unique effects on the cardiovascular system.

Participants will:

1. Undergo baseline measurements of venous thrombosis markers, blood pressure, and measures of arterial function using ultrasound.
2. Be randomized to either take a Plan B® or placebo pill
3. Repeat baseline measurements of venous thrombosis markers, blood pressure, and measures of arterial function using ultrasound each hour, for 6-hours, and then 24- and 48- hours after taking the Plan B® or placebo pill.

Conditions

Female

Premenopausal

Study ID

NCT07759635

Start date

Jul 22, 2026

Status verified date

May, 2026

Completion date

Sep 1, 2027

Anticipated

Primary completion date

Jun 1, 2027

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: Female

Age: 18 - 35

Healthy Volunteers: Accepted

Inclusion Criteria:

1. Provide written informed consent.
2. Pre-menopausal female.
3. 18 - 35 years of age.
4. Naturally cycling (i.e., not using any form of hormonal contraception for ≥ 3 months).
5. Eumenorrheic (i.e., experiencing a predictable menstrual cycle lasting 21-45 days).
6. In the surrounding Hamilton area, or able to visit McMaster for study visits.
7. Not pregnant.

Exclusion Criteria:

1. Known hypersensitivity to the active substance levonorgestrel or to any ingredient in this formulation (i.e., levonorgestrel colloidal silicon dioxide, potato starch, magnesium stearate, talc, cornstarch, lactose monohydrate, or any ingredient/excipient in the placebo capsule.
2. Known or suspected pregnancy.
3. At risk of the development of unwanted pregnancy within the past 72 hours.
4. Known, suspected, or history of cardiovascular, metabolic, or musculoskeletal disease.
5. Undiagnosed abnormal vaginal bleeding.
6. Use of anti-HIV drugs, anticonvulsant drugs, antibiotics, rifampicin/rifabutin, ulipristal acetate, Griseofulvin, Hypericum perforatum (St John's wort) or any other drug that may interfere with the normal pharmacokinetic or pharmacodynamic characteristics of the study intervention.
7. Active or history of migraine.
8. A condition or factor that would prevent the use of Plan B®.

Study Design

Enrollment

40 participants

Anticipated

Allocation

Randomized

Intervention Model

Parallel Assignment

Primary purpose

Basic Science

Interventions and Outcome Measures

Arms

experimental: Plan B®

1.5 mg Levonorgestrel

placebo comparator: Placebo

Gelatin capsule

Interventions

Plan B (Levonorgestrel)

1 x dose of 1.5 mg levonorgestrel tablet over encapsulated to mimic placebo.

Placebo (gelatin capsule)

Gelatin capsule over encapsulated to mimic Plan B

Primary outcome measure

  • D-Dimer [ Time Frame: Baseline, 1-hour, 2-hours, 3-hours, 4-hours, 5-hours, 6-hours, 24-hours and 48-hours post-ingestion of Plan B/placebo ]
  • Prothrombin fragment 1+2 [ Time Frame: Baseline, 1-hour, 2-hours, 6-hours, 24-hours, and 48-hours post-ingestion of Plan B/placebo. ]
  • Thrombin antithrombin [ Time Frame: Baseline, 1-hour, 2-hours, 6-hours, 24-hours, and 48-hours post-ingestion of Plan B/placebo. ]
  • P-Selectin [ Time Frame: Baseline, 1-hour, 2-hours, 6-hours, 24-hours, and 48-hours post-ingestion of Plan B/placebo. ]

Central Contacts and Locations

Central contacts

Jenna C Stone, BSc

905-525-9140stonej1@mcmaster.ca

Locations

Vascular Dynamics Lab

Recruiting

Hamilton, Ontario, Canada, L8S 4L8

Contacts

Maureen J MacDonald, PhD

905-525-9140macdonmj@mcmaster.ca

More Information

Sponsor

McMaster University

Last update posted

Aug 12, 2026

Last verified

May, 2026

Keywords

  • Emergency contraceptives
  • Hormonal contraceptives
  • Venous thrombosis
  • Endothelial function

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-09. This information was provided to ClinicalTrials.gov by McMaster University on 2026-08-12.