Andarine is an orally active partial agonist of the androgen receptor (AR). In intact male rats, 0.5 mg andarine daily was shown to reduce prostate weight to 79.4%, and non-significantly increased levator ani muscle weight. In castrated male rats, this dose restored only 32.5% prostate weight, but 101% levator ani muscle weight [4] This suggests that andarine is able to competitively block binding of dihydrotestosterone to its receptor targets in the prostate gland, but its partial agonist actions at the androgen receptor prevent the side effects associated with the antiandrogens traditionally used for treatment of BPH.[5]
Andarine was first described in the literature by 2002.[6][7][8] It completed phase 1clinical trials for cachexia in 2003.[9][10] Three phase 1 trials (1a, 1b, 1c) were completed with the drug involving 86 healthy male and female volunteers.[10]Phase 2 trials were planned for 2004.[10] However, development of andarine was discontinued, reportedly due to findings of visual disturbances in clinical studies.[3][11] Andarine is thought to have been the first SARM to enter human clinical trials.[12]
^Yin D, Gao W, Kearbey JD, Xu H, Chung K, He Y, et al. (March 2003). "Pharmacodynamics of selective androgen receptor modulators". The Journal of Pharmacology and Experimental Therapeutics. 304 (3). American Society for Pharmacology & Experimental Therapeutics (ASPET): 1334–1340. doi:10.1124/jpet.102.040840. PMID12604714. S2CID14724811.
^He Y, Yin D, Perera M, Kirkovsky L, Stourman N, Li W, et al. (August 2002). "Novel nonsteroidal ligands with high binding affinity and potent functional activity for the androgen receptor". European Journal of Medicinal Chemistry. 37 (8): 619–634. doi:10.1016/s0223-5234(02)01335-1. PMID12161060.
^Yin D, Gao W, Kearbey JD, Xu H, Chung K, He Y, et al. (March 2003). "Pharmacodynamics of selective androgen receptor modulators". The Journal of Pharmacology and Experimental Therapeutics. 304 (3): 1334–1340. doi:10.1124/jpet.102.040840. PMID12604714. S2CID14724811.
^Mohler ML, Bohl CE, Jones A, Coss CC, Narayanan R, He Y, et al. (June 2009). "Nonsteroidal selective androgen receptor modulators (SARMs): dissociating the anabolic and androgenic activities of the androgen receptor for therapeutic benefit". Journal of Medicinal Chemistry. 52 (12): 3597–3617. doi:10.1021/jm900280m. PMID19432422. The peripheral and selective anabolic preclinical pharmacodynamic profile of 8 seemed highly promising and 3602 Journal of Medicinal Chemistry, 2009, Vol. 52, No. 12 Award Address stimulated us to pursue landmark clinical trials of the SARMs, andarine 8 and Ostarine.75 Although phase I studies with 8 were successful with no deficiencies noted (March 17, 2004, press release), Ostarine was selected for advanced clinical development based on corporate strategy. Readers are cautioned to note that the name Ostarine is often mistakenly linked to the chemical structure of 8, which is also known as andarine. The chemical structure of Ostarine has not been publicly disclosed. The authors are unable to provide additional information.
^ abc"Form S-1: GTx, Inc". U.S. Securities and Exchange Commission. 22 December 2003. Clinical Trials. We have completed three Phase I clinical trials of Andarine in a total of 86 healthy male and female volunteers. We tested Andarine for safety and tolerance in single and multiple doses. Results from our Phase I trials support once-a-day oral dosing, and no serious adverse events were observed at any single or multiple dose tested. We observed early indications in the multiple-dose Phase I clinical trial in men that Andarine promoted growth activity, as measured by levels of a growth factor in the blood known as IGF-1, without affecting the sebaceous glands. We believe that these observations support the potential ability of Andarine to selectively modulate androgen receptors in a tissue-specific manner.
^Starcevic B, Ahrens BD, Butch AW (May 2013). "Detection of the selective androgen receptor modulator S-4 (Andarine) in a doping control sample". Drug Testing and Analysis. 5 (5): 377–379. doi:10.1002/dta.1466. PMID23427117. S-4 [Andarine, S3-(4-acetylamino-phenoxy)-2-hydroxy-2-methyl-N-(4-nitro-3-trifluoromethyl-phenyl)-propionamide] a member of the aryl propionamide class of SARMs was evaluated in a phase I clinical trial, but the study had to be stopped due to adverse side-effects involving visual disturbances.[3]
^"Form 8-K". U.S. Securities and Exchange Commission. 3 March 2004 – via Oncternal Therapeutics, Inc. We believe Andarine represents the first SARM to enter human clinical trials.