YK-11 5mg Capsules

Description

What Is YK-11?

YK-11 is a steroidal selective androgen receptor modulator (SARM) that uniquely functions as both an androgen receptor partial agonist and a myostatin inhibitor. First described by Japanese researcher Yuichiro Kanno in 2011, YK-11 is structurally derived from the 19-nor steroid backbone but exhibits a pharmacological profile distinct from traditional anabolic steroids due to its selective receptor modulation and follistatin-inducing properties.

What distinguishes YK-11 from all other characterized SARMs is its dual mechanism: beyond direct androgen receptor activation in muscle tissue, YK-11 stimulates the production of follistatin, a glycoprotein that binds and neutralizes myostatin, the primary negative regulator of skeletal muscle growth. By suppressing myostatin signaling, YK-11 effectively removes the biological ceiling on muscle hypertrophy, a mechanism that has generated substantial research interest in muscle biology, cachexia models, and genetic regulation of muscle mass. The compound demonstrates oral bioavailability and a half-life of approximately six to ten hours.

Key Features and Specifications

Mechanism of Action: How YK-11 Works

YK-11 operates through a dual mechanism that is unparalleled among SARM compounds. First, it binds to androgen receptors in muscle and bone tissue as a partial agonist, activating anabolic gene expression programs including upregulation of myogenic differentiation factors and protein synthesis pathways. Second, and critically, YK-11 induces the expression of follistatin in C2C12 myoblasts, directly measured through increases in follistatin mRNA and protein levels.

Follistatin binds myostatin (GDF-8) with high affinity, preventing myostatin from activating its receptor (ActRIIB) and the downstream Smad2/3 signaling cascade that normally limits muscle growth. By increasing follistatin production, YK-11 effectively lifts the myostatin-imposed brake on muscle hypertrophy, allowing for muscle growth beyond what androgen receptor activation alone can achieve. This mechanism mirrors the phenotype seen in myostatin-knockout animals, which exhibit dramatically increased muscle mass.

In vitro studies confirm that YK-11 increases follistatin expression in a dose-dependent manner and that this effect is androgen receptor-dependent, linking both mechanisms into a unified signaling pathway. The compound also stimulates protein kinase B (Akt) phosphorylation, further enhancing anabolic signaling in skeletal muscle cells.

Reported Research Applications and Benefits

Myostatin inhibition research represents the primary and most novel application for YK-11. The compound’s ability to increase follistatin production provides researchers with an orally bioavailable tool for studying the myostatin-follistatin axis, muscle growth regulation, and the therapeutic potential of myostatin pathway modulation in muscle wasting conditions, genetic myopathies, and age-related sarcopenia.

Skeletal muscle hypertrophy studies have documented that YK-11 promotes muscle cell differentiation and increases myotube diameter in cell culture, with effects that exceed those produced by equivalent concentrations of DHT. This supraphysiological anabolic potential, driven by the combination of AR activation and myostatin suppression, has made YK-11 a key compound in muscle biology research.

Bone metabolism research has shown that YK-11 stimulates osteoblast differentiation through androgen receptor-mediated activation of bone morphogenetic protein (BMP) signaling pathways. Increases in osteocalcin, osteoprotegerin, and alkaline phosphatase have been documented, suggesting applications in osteoporosis and bone regeneration studies.

YK-11 Dosage Information for Research

Due to YK-11’s steroidal structure and moderate half-life, research protocols typically employ split dosing. The compound’s potent dual mechanism warrants conservative dose escalation, and comprehensive blood panel monitoring including testosterone, LH, FSH, and liver function markers is recommended throughout research protocols. Post-cycle therapy is generally incorporated in protocols lasting six weeks or longer.

YK-11 vs LGD-4033: Key Differences

Storage and Handling Instructions

Store YK-11 capsules at controlled room temperature between 20°C and 25°C (68°F to 77°F) in the original sealed container. Protect from direct sunlight, excessive heat, and humidity. Under recommended storage conditions, YK-11 capsules maintain full potency for at least 24 months from the date of manufacture. Do not freeze.

Why Choose PrymaLab YK-11 Capsules

Every batch of PrymaLab YK-11 undergoes rigorous independent third-party testing using HPLC for purity determination and mass spectrometry for structural identity confirmation. Each order includes a batch-specific Certificate of Analysis documenting ≥99% purity, heavy metal screening, residual solvent analysis, and microbial testing. Pharmaceutical-grade encapsulation delivers precise 5 mg dosing per capsule, and free priority shipping is included on all domestic orders.

Frequently Asked Questions About YK-11

How does YK-11 inhibit myostatin?

YK-11 does not directly bind or block myostatin. Instead, it stimulates the production of follistatin, a naturally occurring glycoprotein that binds myostatin with high affinity and prevents it from activating its receptor (ActRIIB). This indirect inhibition mechanism is androgen receptor-dependent and increases in a dose-dependent manner in cell culture models.

Is YK-11 a steroid or a SARM?

YK-11 is classified as a steroidal SARM. While its chemical backbone is derived from the 19-nor steroid scaffold, it exhibits selective androgen receptor modulation rather than the broad systemic androgenic activity of traditional anabolic steroids. Its myostatin-inhibiting properties via follistatin induction are unique among both SARMs and steroids.

What is the half-life of YK-11?

The estimated plasma half-life of YK-11 is approximately six to ten hours based on available pharmacokinetic data. This relatively short half-life supports split dosing protocols, with most research designs administering doses twice daily to maintain more stable circulating concentrations throughout the study period.

Does YK-11 require post-cycle therapy?

Yes. Due to its steroidal structure and moderate suppressive potential, YK-11 research protocols lasting six weeks or longer typically incorporate post-cycle therapy using SERMs such as enclomiphene or clomiphene. Comprehensive hormone panels before, during, and after research protocols are strongly recommended.

Can YK-11 be stacked with other compounds in research?

Published research protocols have investigated YK-11 in combination with non-steroidal SARMs and non-hormonal compounds like GW-501516. The unique myostatin-inhibiting mechanism of YK-11 complements standard AR-agonist SARMs by addressing a separate growth-limiting pathway. Stacking protocols require comprehensive monitoring due to cumulative suppressive potential.

Quality Assurance and Testing

PrymaLab enforces rigorous quality standards for all YK-11 products. Each production batch is independently tested by accredited third-party laboratories using HPLC purity analysis, mass spectrometry identity confirmation, heavy metal screening, residual solvent testing, and microbial assessment. Batch-specific Certificates of Analysis are provided with every order for complete analytical transparency and research documentation.

Research Disclaimer

YK-11 is sold strictly for laboratory research and scientific investigation purposes only. This product is not intended for human consumption, veterinary use, or therapeutic application. YK-11 has not been approved by the FDA or any regulatory agency for medical use. Purchasers must be qualified researchers affiliated with accredited institutions or licensed research organizations. By purchasing this product, you confirm that it will be used exclusively in accordance with all applicable local, state, and federal regulations governing research materials.