SARMs are designed molecules that can be delivered orally, but selectively target androgen receptors in different tissues differently. The goal is to encourage tissues that are the target to respond as they would to testosterone while other tissues where undesirable side-effects are produced will not.
Thus far, the SARMs developed to selective for anabolic effects in muscle or bone tissues also produce an androgenic effects in tissues such as the prostate gland. However several non-steroidal androgens show a ratio of anabolic to androgenic effects of greater than 3:1 and up to as much as 10:1, compared to testosterone, which has a ratio of 1:1.
This indicats that while SARMs are likely to show some virilizing effects when used at high doses (such as those that might be used by bodybuilders), at lower therapeutic doses may be effectively selective for anabolic effects.
The first-generation SARMs developed to date are all orally active without being hepatotoxic (causing liver damage). Those anabolic steroids that aren't active orally must be injected, and those anabolic steroids that are orally active have been associated with dose-dependent liver stresas and even damage.
Research into more potent and selective SARMs continues, as well as efforts to increase oral bioavailability and half-life. Since the first tissue-selective SARMs were only developed in 2003, the compounds tested so far represent only the first generation. Future development may produce more selective agents compared to those available at present.
Articles and Information
The following are links to various articles with information about SARMs and other supplements