Micronized Progesterone for Muscle Growth

(MP4 MPS Trial)

Overseen By Stuart Phillips, Ph.D.

Age: 18 - 65

Sex: Female

Trial Phase: Phase 1

Sponsor: McMaster University

Must not be taking: Hormonal contraceptives, Glucocorticoids, Anticoagulants, others

Disqualifiers: Pregnancy, Tobacco use, Neuromuscular disorders, others

Compensation: Varies

Number of Visits: 2

Duration: 1 day

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial explores whether micronized progesterone, a form of hormone therapy, affects muscle growth in response to exercise. The researchers aim to determine if progesterone alters protein synthesis in muscles post-workout and its impact on the difference between an exercised and a resting leg. Participants will receive either progesterone or a placebo, perform leg exercises, and provide muscle samples for comparison. The study seeks healthy premenopausal women with regular menstrual cycles who are not using hormonal birth control. As a Phase 1 trial, the research focuses on understanding how the treatment works in people, offering participants the opportunity to be among the first to receive this new treatment.

Will I have to stop taking my current medications?

The trial requires that you have not used hormonal contraceptives or medications affecting protein metabolism in the past 3 months. If you are taking these or similar medications, you may need to stop them before participating.

Is there any evidence suggesting that micronized progesterone is likely to be safe for humans?

Research has shown that micronized progesterone, such as the brand PROMETRIUM®, is usually well-tolerated. In past studies, fewer than 5% of people reported side effects like dry mouth. This medicine has FDA approval for other uses, indicating its safety in those contexts.

However, possible side effects should be noted. Common ones include dizziness, bloating, and headaches. Serious side effects are rare but can include allergic reactions or mood changes. Taking large doses for extended periods might increase risks like heart attacks or strokes, especially when combined with estrogen.

In this study, participants will take two doses totaling 400 mg. This is a relatively low amount and only for a short duration, reducing the chance of serious side effects. If there are concerns, discussing them with the study team or a doctor is advisable. ^{1 2 3 4 5}

Why do researchers think this study treatment might be promising?

Most treatments for muscle growth focus on factors like protein supplementation, resistance training, or anabolic steroids. But micronized progesterone works differently, targeting hormonal pathways that can influence muscle development. Researchers are excited because this treatment uses progesterone, a hormone not typically associated with muscle growth, suggesting a novel approach to enhancing muscle mass. This could potentially offer a safer alternative to anabolic steroids, with fewer side effects and a unique mechanism that might amplify muscle growth in new ways.

What evidence suggests that micronized progesterone could be effective for muscle growth?

This trial will compare Micronized Progesterone with a placebo to evaluate its effects on muscle growth. Studies have shown that progesterone can promote muscle growth by increasing the rate of protein synthesis. In postmenopausal women, progesterone increased this rate by about 50%, suggesting it might aid muscle building after exercise. Researchers aim to determine if it has similar effects in premenopausal women. The hypothesis is that progesterone could alter muscle response to workouts, enhancing muscle growth. ^{3 6 7 8 9}

Are You a Good Fit for This Trial?

This trial is for healthy premenopausal women aged 18-30 who want to help discover if a hormone called progesterone affects muscle building after exercise. Participants must be willing to take oral capsules, do leg exercises in a lab, and undergo blood tests and muscle biopsies.

Inclusion Criteria

Body mass index (BMI) between 18 and 34.9 kg/m²

In general, good health, as determined by a study-specific health screening questionnaire and medical history review

Reports regular menstrual cycles (21-35 days in length) for the past 3 consecutive months

Exclusion Criteria

Participation in another interventional study involving investigational drugs or invasive procedures within the past 30 days

Known allergy or intolerance to any ingredient in the BOOST® 2.24 nutritional drink

Currently pregnant, planning to become pregnant, or known/suspected to be pregnant

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Pre-treatment

Participants receive two oral doses of micronized progesterone or placebo, 34 and 10 hours before testing

2 days

1 visit (in-person)

Treatment

Participants complete unilateral leg extension exercise, receive an infusion of a stable isotope tracer, and provide blood samples and muscle biopsies

1 day

1 visit (in-person)

Follow-up

Participants are monitored for safety and effectiveness after treatment

4 weeks

What Are the Treatments Tested in This Trial?

Interventions

• Micronized Progesterone
• Placebo

Trial Overview The study is testing whether taking micronized progesterone (PROMETRIUM®) changes the rate of muscle protein synthesis following resistance exercise compared to a placebo. It involves two doses of progesterone or placebo before exercising one leg and then measuring muscle responses.

How Is the Trial Designed?

Group I: Experimental: Micronized Progesterone Experimental Treatment 1 Intervention

Drug - Micronized progesterone (oral capsules; 400 mg total as 2 × 200 mg at \~34 h and \~10 h pre-trial)

Group II: Placebo Comparator: Placebo Placebo Group 1 Intervention

Drug - Placebo (oral capsules; matched schedule and appearance)

Who Is Running the Clinical Trial?

McMaster University

Lead Sponsor

Trials

936

Recruited

2,630,000+

Citations

1. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC3879672/

Testosterone and Progesterone, But Not Estradiol, Stimulate ... In postmenopausal women, both T and progesterone treatment increased the muscle protein fractional synthesis rate by approximately 50% (both P < .01).

2. clinicaltrials.gov clinicaltrials.gov/study/NCT07173361

Progesterone and Muscle Protein Synthesis in ... This study will provide direct evidence on whether progesterone modifies the acute anabolic response to resistance exercise in reproductive-age ...

3. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC11460760/

Hormones, Hypertrophy, and Hype: An Evidence-Guided ... The authors reported similar muscle hypertrophy and strength improvements with no significant correlations between the acute postexercise rise in systemic ...

4. mdpi.com mdpi.com/2813-0413/3/3/24

Hormonal Influences on Skeletal Muscle Function in ... A study involving 200 women using combined HCs showed no significant change in muscle strength over a year, whereas another study with 100 women using ...

5. frontiersin.org frontiersin.org/journals/physiology/articles/10.3389/fphys.2020.596130/full

Transdermal Estrogen Therapy Improves Gains in Skeletal ... HT significantly improved flexion strength in the upper body (∼2–5 kg), whereas exercise only marginally improved flexion strength (∼2 kg) ...

6. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC11594581/

The Potential Health Risks and Benefits of Progesterone in the ... Nevertheless, research indicates that administering oral MP prematurely may impede potential growth [22]. A literature gap prompted investigations into the ...

7. accessdata.fda.gov accessdata.fda.gov/drugsatfda_docs/label/1998/20843lbl.pdf

PRODUCT INFORMATION PROMETRIUM (progesterone ... Other adverse events reported in <5% of patients taking PROMETRIUM Capsules include: Autonomic Nervous System Disorders: dry mouth. Body As A Whole: accidental ...

8. goodrx.com goodrx.com/prometrium/prometrium-side-effects?srsltid=AfmBOopbTznAOM2zRJoKZkuWbFU9f0gNzfSd4rKdXtwgsX605Jm4hwas

7 Prometrium Side Effects You Should Know About Read on to learn about the common and rare side effects of Prometrium (micronized progesterone) and how to manage them.

9. mayoclinic.org mayoclinic.org/drugs-supplements/progesterone-oral-route/description/drg-20075298

Progesterone (oral route) - Side effects & dosage Using large doses of this medicine over a long period of time and using it with an estrogen medicine may increase your risk of heart attack, stroke, blood clots ...