Catalog classification, reference sizes, lab math links, and source-backed data. Educational use only — not medical advice.
Researched for: PepTools vendor-neutral scientific reference catalog
Also known as: M5b, M5-b metabolite, carboxylated LGD-4033 long-term metabolite, LGD-4033 M5-b, (4R,5R)-4-{[4-cyano-3-(trifluoromethyl)phenyl]amino}-6,6,6-trifluoro-5-hydroxyhexanoic acid, bishydroxylated LGD-4033 metabolite
M5-b is the stereochemically defined, ring-opened carboxylated metabolite of LGD-4033: (4R,5R)-4-{[4-cyano-3-(trifluoromethyl)phenyl]amino}-6,6,6-trifluoro-5-hydroxyhexanoic acid. Its structure was revised from an earlier pyrrolidine-based assignment and supported by chemical synthesis, NMR characterization, and comparison with authentic metabolic material.
Source review pending. This descriptive profile is shown from the available source material as a best-effort educational reference. It has not passed the full verification bar and is not a dosing instruction, medical claim, or treatment recommendation.
This record represents a metabolite and analytical reference compound, not the parent SARM. Published human studies describe urinary formation and detectability after controlled micro-dose administration of LGD-4033; these findings are analytical/metabolism data and do not establish a therapeutic use, safety profile, or recommended administration regimen for M5-b itself. Common catalog package sizes were not treated as an appropriate scientific fact and are therefore omitted.
Supplementary research context only. Not medical advice or a treatment recommendation.
Molecular formula: C14H12F6N2O3. Reported exact-mass-related value: m/z 369.0668 for [M-H]-; reported molecular weight in analytical literature: approximately 370.08 u.
M5-b is commonly used by anti-doping laboratories as the primary long-term urinary biomarker for LGD-4033 exposure. It is detected after enzymatic hydrolysis and analyzed by LC-HRMS/MS. M5-a is a closely related isomeric metabolite monitored alongside M5-b.
Reflects published research. Educational reference — not a recommendation for use.
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Published articles on this site that mention M5-b or one of its catalog aliases.
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