OTR-AC Research Material
OTR-AC (CAS 1025658-44-9) is a nonsteroidal arylpropionamide ester derivative of ostarine (MK-2866), supplied as a research material. It is listed here as an ester of a characterised parent rather than as a characterised compound in its own right, because that is what the published record supports.
What is and is not known about this material
There is no published pharmacology for this ester. A PubMed search returns no studies of it: no binding affinity, no transactivation data, no pharmacokinetics, no hydrolysis kinetics, no metabolite identification. Everything below the parent-compound heading describes ostarine, not the material on this page.
The reasoning behind an ester derivative is standard medicinal chemistry — esterifying a hydroxyl group changes lipophilicity, and the ester is expected to hydrolyse back to the parent. But expected is doing real work in that sentence. The rate and completeness of hydrolysis, whether the intact ester has activity of its own, and what fraction ever becomes parent compound are all unmeasured here. Researchers designing work around this material should establish those parameters rather than assume them, and should treat the intact ester and the parent as separate analytes when developing a method.
The parent compound: ostarine
Ostarine is a nonsteroidal arylpropionamide selective androgen receptor modulator targeting the androgen receptor (AR, NR3C4), and is the most thoroughly characterised arylpropionamide in the analytical literature.
Metabolic routes. In liver S9 incubations the principal routes are monohydroxylation, nitro-reduction, dephenylation and demethylation; in vivo these combine with glucuronidation, sulfation and carboxylation. The intact parent dominates and is the practical analyte.[1]
Trace-level detection. Quantified in hair at 3–21 pg/mg.[2] Covered by validated urine screening methods across nine SARM chemical classes.[3]
Research Applications
Given the absence of characterisation data, the honest applications are the ones that would generate it:
Hydrolysis and stability studies establishing whether, how fast and how completely the ester converts to ostarine under defined conditions.
Analytical method development treating intact ester and parent as separate analytes.[1,3]
Comparative AR binding and transactivation of ester against parent, to establish whether the intact molecule has activity of its own.
Analytical Documentation
Purity and identity vary by manufacturing lot. Kimera Chems does not publish a single fixed purity figure for this item; refer to the batch-specific Certificate of Analysis (COA) issued for the lot received, which reflects third-party analytical testing for that lot. For an ester or a multi-component blend the COA is the only document that speaks to what is actually in the vial.
References
These references describe the parent compound(s). None of them studied the material on this page.
- de Rijke E, Essers ML, Rijk JCW, et al. Selective androgen receptor modulators: in vitro and in vivo metabolism and analysis. Food Addit Contam Part A. 2013;30(9):1517–1526. doi:10.1080/19440049.2013.810346
- Kintz P, Gheddar L, Ameline A, Raul JS. Perspectives in evaluating selective androgen receptor modulators in human hair: a short communication. Ther Drug Monit. 2021;43(2):298–300. doi:10.1097/FTD.0000000000000859
- Stacchini C, Botrè F, Comunità F, et al. Simultaneous detection of different chemical classes of selective androgen receptor modulators in urine by liquid chromatography-mass spectrometry-based techniques. J Pharm Biomed Anal. 2021;195:113849. doi:10.1016/j.jpba.2020.113849
Storage & Handling
Store at controlled room temperature. Keep tightly closed. Liquid formats: do not refrigerate or freeze. Cold storage may cause the solution to cloud or precipitate. If this occurs, return to room temperature and mix until clear.
Storage guidance is a house recommendation. Analytical documentation is per-lot release testing.
