We all know that it’s been a while since a new SARM (Selective Androgen Receptor Modulator) hit the market. But now everyone’s wait is over, as OTR-AC has arrived.
Ostarine O-Acetate (OTR-AC) is a potent SARM that has also shown cardiovascular and antioxidant properties. It is an upgraded version of Ostarine, a SARM. OTR-AC is more potent than Ostarine and has shown more effective results.
While OTR-AC is related to Ostarine, they have distinct differences. In this blog, we’ll explore what sets OTR-AC apart and how it compares to Ostarine and examine their dosages.
Ostarine vs. OTR-AC
Let’s take a look at a comparison table of OTR-AC vs. Ostarine.
OTR-AC | Ostarine |
Known in the market by the name Ostarine O-Acetate, or Ostarine Ester | Known in the market by the names Ostarine, MK-2866, and Enobosarm |
Higher potency due to acetylation | Ostarine lacks acetylation |
Improved bioavailability for better absorption | Standard bioavailability |
Offer muscle growth, fat loss, cardiovascular, and antioxidant effects | Offer muscle growth and fat loss effects with enhanced stamina |
A lower dose is recommended due to high potency around 5 – 15 mg/day | Generally, a high dose is recommended due to moderate potency, e.g., 20 – 30 mg/day |
It is believed to have a long half-life of around 36 – 48 hours | The half-life of Ostarine is around 24 hours |
No frequent doses are needed as it stays in the body for a longer time | It requires frequent doses due to its short half-life |
What is Ostarine (MK-2866)?

Ostarine, also known as MK-2866 or Enobosarm, is a selective androgen receptor modulator (SARM). It is widely known for promoting muscle growth, reducing excess fat, and preventing muscle wasting.
It works by specifically targeting androgen receptors. By targeting these receptors, it stimulates anabolic activity in muscles and bones without offering the effects one would expect from steroids.
Ostarine is popular among fitness enthusiasts due to its muscle-building effects. It is also known for its fat loss and stamina-enhancing effects. Furthermore, it is being studied for its potential therapeutic uses in conditions like osteoporosis and muscle-wasting diseases.
Besides, Ostarine has a short half-life of 24 hours. It means that it leaves your system after 24 hours. Since it leaves your system soon, you may need frequent dosing to feel its effect for a longer time.
Potential Benefits of Ostarine
Different studies on Ostarine SARM have shown its following potential benefits:
- Improves Muscle Mass
- Enhance Endurance
- Help With Fat Loss
- Aid in Recovery
- Good for Cutting and Bulking Phases
Potential Side Effects of Ostarine
Just like any other SARM, Ostarine also has a few side effects, including
- Liver Stress
- Hormonal Imbalance
- Joint Pain
- Fatigue
- Headache and Dizziness
What is OTR-AC?

Ostarine O-Acetate (OTR-AC) is a modified version of Ostarine and is made after the esterification process.
OTR-AC enhances the effects of Ostarine greatly and prolongs its half-life. This version has improved bioavailability, and it remains active in the system for a longer period than Ostarine.
OTR-AC works similarly to Ostarin,e but its effects on the body are 10 times better, i.e., more muscle growth and fat reduction. Plus, it shows cardiovascular and antioxidant protection which, in the case of Ostarine, has not been studied.
Potential Benefits of OTR-AC
OTR-AC is believed to have the following benefits:
- Significantly Enhances Muscle Growth
- Boost Fat Loss
- Improved Bone Health
- Faster Recovery
- Enhance Performance
- Muscle Preservation During Cutting Cycle
- Cardiovascular Effects
- Antioxidant Effects
Potential Side Effects of OTR-AC
Since OTR-AC is more potent than Ostarine, its side effects may be more pronounced.
- Possible Estrogenic Effects
- Mood Swings and Increased Aggression
- Appetite Changes
- Mild Testosterone Suppression
- Hormonal Imbalance
Recommended Dosage for Ostarine and Cycle Duration
Individuals who have taken OTR-AC have shared their experiences. We have created a dosage table based on their experience.
Dosage Strength | Maximum Cycle Length |
10 mg for beginners 20 mg for intermediate 30 mg for more experienced | 8 – 12 weeks |
Can be split and taken with food | — |
Recommended Dosage for OTR-AC and Cycle Duration
Dosage Strength | Maximum Cycle Length |
10 – 30 mg per day. Remember 30 mg is for more experienced users. | 8 weeks, and for best results, take it for 8 – 12 weeks. |
Beginners should start with a low dose of 10 mg. | — |
Split the dose: take one in the morning, one in the afternoon, and one in the evening with food. | — |
Disclaimer
The information provided is for informational purposes only and should not be considered medical advice. Readers should consult with a healthcare professional before using OTR-AC and Ostarine or any other supplement.
Final Verdict:
Ostarine is a SARM that offers muscle-building effects. It has a short half-life of 24 hours. OTR-AC, on the other hand, is a more potent and advanced version of Ostarine. It offers greater muscle growth, fat loss, and cardiovascular and antioxidant benefits. It has a longer half-life of approximately 36–48 hours and stays in the system longer.
However, its stronger effects may lead to more pronounced side effects. Both SARMs are effective, with OTR-AC standing out for their enhanced bioavailability and longer-lasting impact.