OTR AC Guide – Dosage, Cycling, Side Effects

OTR-AC is a SARM that has been shown to increase muscle through the Androgen Receptors. It's a form of Ostarine that has been altered for improved performance.

Are you tired of looking like a boiled chicken at the gym? Well, you’re not alone! According to a recent survey, 87% of gym-goers wish they could bulk up their muscles faster. 

But fear not, my fellow fitness fanatics, because OTR-AC is here to save the day! 

This little molecule is like a personal trainer on steroids (figuratively speaking, of course). It helps you put on dry, lean muscle mass while also cutting down on unwanted fats. 

It’s quite literally like the superhero of SARMs! 

In this review, we’ll dive into the nitty-gritty of OTR-AC and show you why it’s the secret weapon you need to take your bodybuilding journey to the next level. 

So, put on your gym shorts, grab your protein shake, and let’s get ready to pump some iron with OTR-AC!”

Warning: The content on Muscleandbrawn.com and the information included in this article is intended for entertainment and informational purposes only. It is not intended nor implied to be a substitute for professional medical advice. Prior to buying anything, check that it is compliant where you live with your current government laws. We frequently mention research chemicals that are not made for human consumption. Therefore, before purchasing any product for personal use, consult with your doctor or healthcare provider first.

Key Takeaways:

  • OTR-AC is a form of SARM known as Ostarine. It has undergone esterification, which increases its potency, half-life, and biodistribution.
  • OTR-AC helps to build lean muscle mass while cutting down on unwanted fats, and bodybuilders and fitness enthusiasts use it for its muscle-building benefits.
  • It can also improve physical function in elderly individuals and cancer patients with muscle wasting.

What is OTR-AC?

Ostarine, also commonly known as MK-2886, is a type of selective androgen receptor modulator (SARM) drug. It has a chemical structure known as aryl-propionamide, and it is categorized as a non-steroidal compound. 

OTR-AC is a form of Ostarine that has undergone esterification. This is an important part in the production of OTR-AC because it maximizes potency and biodistribution and increases half-life by 10-folds. Once it is esterified, it is referred to as OTR-AC or MK-2886 ester.

How does OTR-AC work?

To understand the mechanism of action of OTR-AC, we must first look into the workings of the selective androgen receptor modulators as a collective group of compounds. 

As the name implies, compounds that fall into the category of SARM have the ability to stimulate the androgen receptors in the body. Interestingly, these compounds partially mimic androgens by acting only on skeletal muscle tissue and therefore are a go-to choice for muscle building. 

Like androgens, OTR-AC enters the cytoplasm of a cell and binds to androgen receptors. Then it translocates to the nucleus where the androgen receptor’s interaction with OTR-AC acts as a transcriptional regulator, which recruits cofactors and co-regulatory proteins. (1

This action of acquiring only a specific kind of co-regulatory protein allows OTR-AC to regulate gene expressions and bring about a number of diverse changes in the body.

The most important and well-recognized effect of OTR-AC is an increase in muscle growth. OTR-AC increases muscle fibers, capillary density, and muscle enzyme activity while simultaneously promoting the proliferation of muscle tissue. (2

When muscle mass in the body increases, more energy is required for the functioning and repair of muscle cells. This energy is primarily derived from the breakdown of fat cells in the body, as a result of which the amount of fat stored in the body decline in people who are taking OTR-AC. (3

By reducing body fat, OTR-AC also helps in lowering cholesterol levels, specifically low-density lipoprotein, which can have serious adverse effects on cardiac health. This is particularly seen in post-menopausal women who are at a greater risk of cardiac events.

Some clinical trials have also concluded that subjects that were treated with OTR-AC showed a decrease in fasting blood glucose, insulin levels, and insulin resistance. (4

Laboratory research done on ovariectomized rats found that OTR-AC had significant effects on bone healing. It improved callus formation and bone mineral density and also accelerated the time it took for osteotomy to heal. Similarly, it can also contribute to the rapid healing of skeletal muscles. (5

Benefits of OTR-AC

After having closely looked at the mechanism of action of OTR-AC, appreciating its benefits wouldn’t be as difficult!

  • Despite its effects on different mechanisms in the body, OTR-AC is primarily a muscle-building drug that is specifically beneficial for bodybuilders. It helps in attaining a total lean body mass that provides greater strength and improved performance to athletes as well as gym enthusiasts. 
  • Other than for recreational purposes, the use of this drug becomes essential in sarcopenia, which is age-related muscle wasting. Research reveals that OTR-AC improved the ability of elderly men and women to climb stairs. (6
  • Similarly, in conditions like cancer cachexia, there is excessive muscle wasting which results in weakness and decreases overall physical function. Thus in cancer patients, OTR-AC can improve physical function by increasing muscle mass. (7
  • The ability of OTR-AC to reduce body fat poses another benefit for fitness enthusiasts who want to lose fat without losing their muscle mass. Subsequently, it can solely be used as a weight-reducing agent in obese patients as well. 
  • By decreasing the LDL levels in the blood, OTR-AC acts as a cardio-protective agent, thereby preventing the formation of clots which may lead to cardiac ischemia and other conditions.
  • OTR-AC has proven to be an effective healer of muscle and bone, which makes it a potent drug for people who may suffer from injuries quite often. These include athletes and bodybuilders who require rapid wound healing in order to continue with their fitness routine. (8)
  • The effects of OTR-AC on glucose metabolism in the body help it in overcoming insulin resistance, which indicates that it can be used by patients with diabetes. 

OTR-AC is a fitness drug that has gained popularity among fitness enthusiasts. Despite its effects that have been explored through animal research, it has not been approved by the FDA. 

 Who should use OTR-AC?

OTR-AC is the perfect drug for bodybuilders because of its skeletal muscle stimulation properties! It helps them in bulking up and provides them with the required strength to carry on with their fitness routines.

It is also designated as an effective stimulator of muscle mass in patients suffering from cancer cachexia and sarcopenia and thus subsequently elevates their quality of life.

As OTR-AC improves muscle and bone regeneration, it can be used by people who are looking for a quicker recovery. This may also apply to conditions like postmenopausal osteoporosis.  

Furthermore, OTR-AC can be administered to post-menopausal women as a cardio-protective agent, whereby it reduces cholesterol levels and reduces the risk of cardiac diseases.

Forms of OTR-AC

OTR-AC is mostly available for human consumption in the form of a capsule or a tablet since it is a relatively easier method of administration. 

Another popular form is the OTR-AC liquid, which is said to have greater bioavailability. Other less common forms include OTR-AC powder. 

How To Use OTR-AC

It is recommended that OTR-AC should be taken in the morning before a workout session.

It is also important to note that this drug should be avoided during breastfeeding and pregnancy because the current scientific literature does not provide enough evidence on its effect on prenatal development. 

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

10 mg capsules of OTR-AC should be administered thrice a day, which makes up the daily recommended dose of 30 mg. 

This OTR-AC cycle can be continued for a minimum of 8 weeks, in which most users have given positive feedback. It can be continued for a maximum of 12 weeks, after which it is necessary to give a gap for the hormones in the body to normalize. 

OTR-AC Stacks

OTR-AC is often taken alongside Ligandrol and Testolone, which are both anabolic SARMs. These drugs together form a stack that helps in building muscle mass.

For the purposes of losing fat, OTR-AC can be stacked with Cardarine or Stenabol, which helps in burning extra fat by modulating the metabolic processes.  

OTR-AC Reviews

Because the use of SARMs can be a bit risky in terms of the adverse effects associated, it is very important to dig into some of the user reviews and see the ACTUAL results!

One of the users said,

“I don’t recommend anything over 15mg eod. Start low, maybe 5-10. Honestly, ostarine is probably better. Otr-ac mostly has more sides, and about the same results as ostarine. Def higher aggression, more strength. But severe insomnia, high BP, increased anxiety not rly worth it. Rad is probably better if you want that.”

Another one said,

“Pretty sure it’s basically ostarine with a really long half-life. Dosing should be the same.”

One of the users gave a very comprehensive review saying,

“First week my traps looked a bit bigger and I had thought it was placebo. My libido had increased, feeling like a horn dog. Acne flare ups on my face only but gone already. No shedding or gyno. Slight ball ache on the right nut. Feeling a bit more motivated overall.

Second week currently, my traps definitely got bigger; not even placebo thoughts about it anymore. It grew to a point where it sticks out some of my jackets when I workout or when my hands are in my pockets.”

OTR-AC Side Effects

OTR-AC is generally a user-friendly SARM, with studies suggesting that up to 100mg of the drug can be administered in a day safely.

Since this drug is mostly ingested orally, there are chances of it leading to liver damage. Heart attack as a side effect of OTR-AC has also been reported.    

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Where Can I Buy OTR-AC?

A lot of people still merely consider OTR-AC and Ostarine similar, due to which not many online vendors offer OTR-AC as of yet.

#1 SARM Supplier Online

OTR-AC from Chemyo

Ostarine, also commonly known as MK-2886, is a type of selective androgen receptor modulator (SARM) drug. It has a chemical structure known as aryl-propionamide, and it is categorized as a non-steroidal compound. 

OTR-AC is a form of Ostarine that has undergone esterification. This is an important part in the production of OTR-AC because it maximizes potency and biodistribution and increases half-life by 10-folds. Once it is esterified, it is referred to as OTR-AC or MK-2886 ester.

What I would recommend is that if you are planning to use OTR-AC, just buy it from any trusted vendor that you can get the hang of.

OTR-AC vs. Other SARMs

OTR-AC vs. Testolone (RAD 140)

Both these drugs are potent anabolic agents and a part of SARMs, therefore, they bring about changes by binding to the androgen receptors. One of the most prominent changes brought about by these SARMs is the increase in muscle mass.

Testolone, however, is a potential treatment for Alzheimer’s disease, therefore, has cognitive benefits which ORT-AC does not extend. Testolone is also comparatively more expensive.

OTR-AC vs. Stenabolic (SR9009)

OTR-AC and Stenabolic are SARMs that are often stacked together to increase fat metabolism and thereby achieve weight loss.

OTR-AC, on the one hand, is a widely studied SARM and has the least side effects as compared to Stenabolic, in which issues with digestion and nausea have been reported. Moreover, it is primarily used for increasing endurance in bodybuilders, whereas OTR-AC is a muscle-building drug. 

Is OTR-AC Legit?

OTR-AC has brought about drastic effects in the body of people who have used it for muscle gain, and therefore it’s considered among the most universally suitable SARMs. 

Its efficacy as a fat loss SARM has also been frequently tested, which makes it more attractive for anyone who wants to get started with their fitness journey.

Some of its other additional benefits, such as on cognition and heart health, have not been studied in depth. Thus more research using human subjects will help clear any ambiguities regarding the use of this drug and will provide affirmation of its efficacy.

If you were to take my opinion, maybe wait for a few years till we get something solid on OTR-AC in terms of the latest scientific research as well as more user experiences because it can get a bit risky.


Does OTR-AC increase testosterone?

OTR-AC is more potent than Ostranine and builds a lean physique by increasing testosterone levels and enhancing its effect on muscles.

What is OTR-AC used for?

Studies suggest that OTR-AC, along with other SARMs, increases muscle mass and strength by stimulating the formation of muscle tissue: In older adults, the administration of SARMs, including OTR-AC resulted in increased lean muscle mass and decreased body fat percentage.

What is the most powerful SARM?

Testolone Rad 140 is one of the most potent SARMs on today’s market and one of the newest. Many bodybuilders take Testolone to increase muscle endurance and build lean mass.

Which SARM is best for bulking?

The most effective and strongest SARMs to use for building muscle during the bulking phase are Testolone RAD 140, Ligandrol LGD-4033, Ibutamoren MK677, and Ostarine MK2866.

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1)Hikichi, Y., Yamaoka, M., Kusaka, M., & Hara, T. (2015). Selective androgen receptor modulator activity of a steroidal antiandrogen TSAA-291 and its cofactor recruitment profile. European journal of pharmacology, 765, 322–331. https://doi.org/10.1016/j.ejphar.2015.08.052

2)Leciejewska N, KoΕ‚odziejski PA, Sassek M, Nogowski L, MaΕ‚ek E, PruszyΕ„ska-OszmaΕ‚ek E. Ostarine-Induced Myogenic Differentiation in C2C12, L6, and Rat Muscles. International Journal of Molecular Sciences. 2022; 23(8):4404. https://doi.org/10.3390/ijms23084404

3)Solomon, Z. J., Mirabal, J. R., Mazur, D. J., Kohn, T. P., Lipshultz, L. I., & Pastuszak, A. W. (2019). Selective Androgen Receptor Modulators: Current Knowledge and Clinical Applications. Sexual medicine reviews, 7(1), 84–94. https://doi.org/10.1016/j.sxmr.2018.09.006

4)Narayanan, R., Mohler, M. L., Bohl, C. E., Miller, D. D., & Dalton, J. T. (2008). Selective androgen receptor modulators in preclinical and clinical development. Nuclear receptor signaling, 6, e010. https://doi.org/10.1621/nrs.06010

5)Komrakova, M., FurtwΓ€ngler, J., Hoffmann, D.B. et al. The Selective Androgen Receptor Modulator Ostarine Improves Bone Healing in Ovariectomized Rats. Calcif Tissue Int 106, 147–157 (2020). https://doi.org/10.1007/s00223-019-00613-1

6)Narayanan, R., Coss, C. C., & Dalton, J. T. (2018). Development of selective androgen receptor modulators (SARMs). Molecular and cellular endocrinology, 465, 134–142. https://doi.org/10.1016/j.mce.2017.06.013

7)Zilbermint, M. F., & Dobs, A. S. (2009). Nonsteroidal selective androgen receptor modulator Ostarine in cancer cachexia. Future oncology (London, England), 5(8), 1211–1220. https://doi.org/10.2217/fon.09.106

8)Komrakova, M., Nagel, J., Hoffmann, D. B., Lehmann, W., Schilling, A. F., & Sehmisch, S. (2020). Effect of Selective Androgen Receptor Modulator Enobosarm on Bone Healing in a Rat Model for Aged Male Osteoporosis. Calcified tissue international, 107(6), 593–602. https://doi.org/10.1007/s00223-020-00751-x


Kumar Rathi

Kumar Rathi | Writer

Kartik is a medical student with a passion for anatomy and physiology. He writes research papers, articles and blogs to raise awareness and also has a strong interest in teaching and public speaking. Aspiring to be a successful cardiologist, Kartik believes in connecting with people on a personal level and is an expert in peptides.

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Chemical Structure

Mechanism of Action

OTR-AC belongs to a group of compounds which are known as selective androgen receptor molecules (SARM). As the name implies, this drug has the ability to bind to the androgen receptor but only partially stimulates it. Most of its effect is seen in the skeletal muscle where it stimulates the proliferation of cells and helps in increasing muscle mass. It also aids in fat loss from the body by increasing the metabolism of adipose tissue. By reducing fats stores, OTR-AC can also prevent the risk of thrombus formation and any other cardio-vascular diseases.

Class of Compound

Selective androgen receptor molecule (SARM)

Street Names

OTR-AC, MK-2886 ester, Ostarine


Increases muscle mass , Promotes fat loss , Promotes quick bone and muscle healing

Side Effects and Dangers

Liver damage , Heart attack

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