OTR-AC (Ostarine O-Acetate) Dosage, Benefits, Side Effects and Other Relevant Details



OTR-AC (Ostarine O-Acetate)

What is OTR-AC?

Vial containing OTR-AC (Ostarine O-Acetate)

OTR-AC, also known as Ostarine O-Acetate, is a modified form of the chemical MK-2866, better known as Ostarine. It was modified during its development to make it more potent and have a longer-lasting effect on the body. This alteration involves an esterification process, which improves its effectiveness, how it distributes throughout the body, and how long it remains active.

Ostarine, in general, belongs to a class of drugs known as Selective Androgen Receptor Modulators (SARMs). These compounds interact with androgen receptors, which are proteins in the body. When Ostarine binds to these receptors, it can stimulate muscular development. Ostarine, unlike standard anabolic substances, is non-steroidal and does not go through some of the regular chemical changes that might contribute to undesired side effects found with steroids. As a result, it may be less likely to cause negative effects.

OTR-AC is being studied by researchers for its possible advantages in avoiding muscle-wasting illnesses and increasing muscular development.

Description of OTR-AC (Ostarine O-Acetate)

How Does OTR-AC Work?

Ostarine binds to androgen receptors, which are proteins in the body. When it attaches to these receptors, it may cause muscles to develop.  Selective androgen receptor modulators are a new class of non-steroidal, tissue-specific anabolic agents with the potential to increase muscle mass and improve physical function while avoiding the negative side effects on the prostate, skin, or hair that are commonly associated with testosterone or other non-selective, synthetic anabolic steroids. Ostarine is a SARM that, upon binding, can cause conformational changes in the androgen receptor, modifying the receptor's interaction with coactivator and corepressor proteins found in various tissues and altering the receptor's capacity to control gene expression.

OTR-AC Research

OTR-AC (Ostarine O-Acetate)

Numerous animal and human studies have been conducted on the potential application of OTR-AC. Below are some of the relevant findings:

Cancer Cachexia

Cancer cachexia is a syndrome that causes substantial muscle loss in cancer patients, resulting in physical weakness and degeneration. OTR-AC research has shown promise in this area, with findings showing that it may enhance lean body mass and improve physical function in cancer patients who have lost muscle mass as a result of their disease. This shows that OTR-AC may be able to assist these patients in regaining muscle and strength, hence increasing their overall quality of life.

Lean Body Mass

OTR-AC has been focused on older people, a population that is prone to muscle atrophy and decreased physical function as they age. OTR-AC has been shown in studies to increase lean body mass and physical function in these patients. This shows that OTR-AC may be advantageous for older persons wanting to preserve or restore muscle strength and mobility, both of which are important for maintaining an active and healthy lifestyle in later years.


Researchers are investigating the possibility of OTR-AC in the treatment of endometriosis in women. Endometriosis is a painful disorder in which tissue comparable to the uterine lining develops outside the uterus. According to a preliminary study, OTR-AC may be a safe and effective treatment option for this illness. However, further research is needed to demonstrate its safety and efficacy as a therapy for endometriosis.

Breast Cancer

In patients with a specific type of breast cancer known as Luminal Androgen Receptor Breast Cancer (AR+ TNBC), OTR-AC has shown some level of activity. This suggests that OTR-AC may have the potential as a treatment option for this specific subtype of breast cancer. Further research is required to understand better its effectiveness and safety in treating this condition.


Osteoporosis is a disorder that causes weaker bones that are more prone to fractures. According to research, OTR-AC, and Ostarine in general, may have a favorable effect on bone repair, making it a potentially useful treatment for osteoporosis. However, further research is needed to determine any potential adverse effects and long-term benefits before it can be designated a regular treatment.

Improvement of Muscle Tissue

Ostarine, especially OTR-AC, has been shown in animal studies to improve muscle vascularization, which implies it may increase blood flow to muscles and boost muscular development and activity. This might be useful for athletes or those who want to increase their physical performance and muscular growth. More study, however, is required to discover ideal dosages and evaluate any potential detrimental effects at greater concentrations.


Some preliminary study has suggested that Ostarine, especially OTR-AC, may have therapeutic effects in the management of diabetes. It has been linked to lower fasting blood glucose levels, lower insulin levels, and better insulin resistance in individuals. However, greater research into the precise processes and long-term consequences is required to understand its function in diabetes control further.


Ostarine has been demonstrated in studies to affect cholesterol levels, specifically LDL (bad) and HDL (good) cholesterol. These cholesterol levels appear to be reduced in a dose-dependent manner. More thorough study is needed, however, to establish its efficacy and understand its consequences for overall cardiovascular health.

OTR-AC (Ostarine O-Acetate) Stack well with

OTR-AC (Ostarine O-Acetate)

OTR-AC (Ostarine O-Acetate) Stack well with the following:

OTR-AC Effects

  • Potential to aid the prevention of muscle wasting
  • Potential to improve lean body mass
  • Potential applications in insulin resistance
  • Potential to reduce liver damage

OTR-AC Side Effects

When eaten orally, ostarine may provide a health concern. It will likely cause liver damage as well as other dangerous adverse effects, such as a heart attack.

Is OTR-AC Illegal to Purchase?

OTR-AC can be purchased legally as a research chemical.
It, like other selective androgen receptor modulators, is exclusively for laboratory research usage. Athletes and professionals should avoid this chemical, though, because it is on the World Anti-Doping Agency's list.

The half-life

Because esterification of anabolic drugs leads to a least 10-fold increase in half-life, the active component has the potential to be bioactive for ten times longer than previously.

OTR-AC Dosage

OTR-AC is widely available in different grams of capsules, with 10 mg being the most recommended and used one. 

OTR-AC Cycling

This OTR-AC cycle can be continued for a minimum of 8 weeks, with the majority of users providing good comments. It can be continued for a maximum of 12 weeks before stopping to allow the hormones in the body to normalize.

How To Use OTR-AC

It is advised that OTR-AC be taken in the morning before working out. It is also crucial to mention that this medicine should be avoided during nursing and pregnancy because there is insufficient proof of its influence on fetal development in the scientific literature.

 Is Ostarine the same as Ostarine O Acetate?

Ostarine is not the same as OTR-AC (Ostarine O Acetate). A selective androgen receptor modulator (SARM) called Ostarine, often referred to as MK-2866, is used to increase bone density and muscle mass. OTR-AC is an altered form of ostarine that has an acetate ester added to it so that the body can absorb it more quickly. OTR-AC, a SARM, is thought to have effects that are comparable to those of Ostarine but may be stronger. 


OTR-AC has demonstrated its ability to improve lean muscle mass, reduce body fat, and increase bone mineral density in a clinical study. More long-term randomized clinical trials are needed to understand its safety and efficacy in humans.


  1. OTR-AC (MK-2866 ESTER) SARM - 20MG/ML - 30ML/60ML BOTTLE. (n.d.). UMBRELLA Labs. https://umbrellalabs.is/shop/sarms/sarm-liquid/otr-ac-mk-2866-ester-sarm
  2. Gel, O.A.S., OTR-AC SARMs Gel 20MG (Packs of 5, 10 or 30).
  3. OTR-AC Elite is the latest product by Augmented Labs. OTR-AC (MK-2866 Ester) benefits, dosing, stacking and PCT. SARMs UK at Predator Nutrition. (n.d.). Predator Nutrition | Bodybuilding and Sports Supplements. https://www.predatornutrition.com/articlesdetail?cid=otr-ac-vs-ostarine
  4. Buy OTR-AC for Sale | 99% Pure | USA-Made. (n.d.). BEHEMOTH LABZ. https://behemothlabz.com/product/otr-ac-liquid
  5. OTR AC Guide - Dosage, Cycling, Side Effects. (n.d.). Muscle and Brawn. https://muscleandbrawn.com/sarms/otr-ac-guide/

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