Selective androgen receptor modulators (SARMs) have been developed, aimed at maximizing anabolic effects on muscle and bone without androgenic effects on other tissues, especially the prostate and hair follicles. [SUP],[/SUP] The first trials of these compounds as function promoting therapies have recently been reported. [SUP],,[/SUP] Treatment with GTx-024 (Enobosarm) has been associated with increases in lean body mass and stair climbing ability, without virilizing effects, in healthy older men and women and in patients with cancer cachexia. [SUP],[/SUP] In another trial, 6 months treatment with MK-0773 was well-tolerated and associated with increases in lean body mass, but not muscle strength or physical performance in older women with sarcopenia and mobility limitations. [SUP][/SUP] Finally, in a recent dose finding study another SARM, LGD-4033, increased lean body mass without effecting PSA levels in healthy young men. [SUP][/SUP] As demonstrated by these early studies, these agents will permit the use of androgen-based anabolic therapies in older women and raise the possibility of safely using more potent pharmacological doses to more reliably improve muscle strength not only in older adults but also in the broader context of cancer cachexia and posttraumatic and postoperative rehabilitation. In these latter indications, the shorter duration of treatment and the consistent positive effects on muscle mass (as opposed to strength and function) may well be the important primary therapeutic outcome.
From Testosterone: A Man's Guide :
Oral selective androgen receptor modulators (SARMs) are investigational agents. Studied since 1998, they are still very much in the infancy of their development and marketing. SARMs may be able to provide the benefits of increased muscle mass and bone density, and fat loss that testosterone and other traditional anabolic/androgenic steroids provide but without the unwanted side effects (prostatic enlargement). SARMs are not intended to be a form of testosterone replacement therapy. So, why am I talking about them? Besides replacement therapy, testosterone and other anabolics can be useful in the treatment of certain aspects of disease. This is a topic close to my heart since this kind of medical use saved my life and that of many others. I spent years researching it to co-write the book “Built to Survive: A Comprehensive Guide to the Medical Use of Anabolic Therapies, Nutrition and Exercise for HIV+ Men and Women” (published in 1999 and then two more editions a few years later and available on amazon.com). Excuse me while I digress from the current topic.
SARMs are aimed to have the same benefits as anabolics but without the side effects.
Ostarine is an oral agent that has demonstrated the ability to increase lean body mass and improve muscle strength and performance in postmenopausal women, elderly men, and men and women with cancer cachexia. Ostarine is made by the company GTx's and has been studied in seven Phase I, Phase II, and Phase IIb clinical trials in 582 subjects.
It had no serious adverse events reported, although I am yet to see the data. Ostarine also exhibited no apparent change in measurements of serum prostatic specific antigen (PSA), sebum production (which causes acne), or decreases in blood levels of LH (which hints that it may not affect the HPGA at the doses tested). I have not seen LDL or HDL and hematocrit or hemoglobin data on this product to assess its effect on lipids and red blood cells, respectively. I am also curious about its effect on liver enzymes.
SARMs have anecdotally not helped increase sexual function, so they probably will not replace testosterone for treatment of hypogonadism. They also decrease the body's production of testosterone, just like anabolic steroids do. So, testosterone replacement will most probably be still required with their use for illness or aging associated loss of lean body mass. We await more data on these interesting compounds as they may have the same clinical benefits as anabolic steroids without the stigma and possibly without their side effects.