Mirabegron (YM-178)

Overview

Mirabegron is a non-peptide, small-molecule selective β3-adrenergic receptor agonist FDA-approved in 2012 for overactive bladder at 25–50 mg/day oral dosing. It is also sold as unregulated 'research use only' powder by fine-chemical vendors, despite being a prescription pharmaceutical. Investigational metabolic research has used a supratherapeutic 100 mg/day dose to study brown adipose tissue activation—an off-label, non-approved use. Mirabegron is pharmacologically distinct from WADA-prohibited β2-agonists, though its it is not on the WADA Prohibited List (only beta-2 agonists are prohibited, Category S3).

Mechanism of Action

Mirabegron selectively activates the human β3-adrenergic receptor with reported low-nanomolar potency (~22.4 nM EC50 for cAMP accumulation in vitro, label-corroborated) and approximately 500-fold lower activity at β1/β2 receptors. Clinically, β3-AR activation relaxes detrusor smooth muscle during bladder storage, increasing capacity without impairing voiding contractions. β3-AR is also expressed on human brown and beige adipose tissue, where agonism increases thermogenesis and metabolic rate—the basis for investigational metabolic studies.

Research Summary

Mirabegron is an FDA-approved drug with extensive human data, not a novel research chemical. Approved adult dosing is 25 mg once daily, increased to 50 mg after 4–8 weeks for overactive bladder. A registered clinical trial (NCT04823442) used 100 mg/day for 4 weeks in 14 healthy women, reporting increased brown adipose tissue activity/volume, HDL cholesterol, insulin sensitivity, and resting energy expenditure with no change in body weight or fat mass (O'Mara et al., J Clin Invest 2020, PMID 31961826)—an open-label study without placebo control. Rat studies confirmed selective β3-adrenoceptor agonist activity with bladder-relaxant effects (Hatanaka et al., 2013, PMID 23239087). Ex vivo porcine ureter studies found mirabegron reduced contractility partly via α1-adrenoceptor antagonism, complicating a pure β3-selectivity profile at the ureter (PMC9192402).

Reported Side Effects

• Increased blood pressure (FDA label warning; not recommended in severe uncontrolled hypertension ≥180/110 mmHg)
• Adverse-event signals flagged in real-world pharmacovigilance analysis at approved doses (PMC10982368)
• Supratherapeutic 100 mg/day dose used in metabolic research exceeds approved safety dosing
• Unregulated RUO powder lacks pharmaceutical QC; purity/identity unverified
• Pharmacologically distinct from β2-agonists but doping status unconfirmed against primary WADA text

Compare Mirabegron (YM-178) with Others

Research References

• In vitro and in vivo pharmacological profile of the selective β3-adrenoceptor agonist mirabegron in rats. 2013. PMID 23239087.
• Chronic mirabegron treatment increases human brown fat, HDL cholesterol, and insulin sensitivity (O'Mara AE et al.). 2020. PMID 31961826.
• Examining the safety of mirabegron: an analysis of real-world pharmacovigilance data from the US FDA Adverse Event Reporting System (FAERS) database.
• Mirabegron attenuates porcine ureteral contractility via α1-adrenoceptor antagonism.

Frequently asked questions

Has Mirabegron (YM-178) been independently lab-tested?

Disclosed Labs has collected 1 Certificate of Analysis (COA) for Mirabegron (YM-178) from 1 independent testing lab. 1 vendor has submitted material for testing. Products average 99.8% tested purity across the corpus. Full testing data is available at https://www.disclosedlabs.com/peptides/mirabegron/testing.

How does Mirabegron (YM-178) work?

Mirabegron selectively activates the human β3-adrenergic receptor with reported low-nanomolar potency (~22.4 nM EC50 for cAMP accumulation in vitro, label-corroborated) and approximately 500-fold lower activity at β1/β2 receptors. Clinically, β3-AR activation relaxes detrusor smooth muscle during bladder storage, increasing capacity without impairing voiding contractions. β3-AR is also expressed on human brown and beige adipose tissue, where agonism increases thermogenesis and metabolic rate—the basis for investigational metabolic studies.

What does the research say about Mirabegron (YM-178)?

Mirabegron is an FDA-approved drug with extensive human data, not a novel research chemical. Approved adult dosing is 25 mg once daily, increased to 50 mg after 4–8 weeks for overactive bladder. A registered clinical trial (NCT04823442) used 100 mg/day for 4 weeks in 14 healthy women, reporting increased brown adipose tissue activity/volume, HDL cholesterol, insulin sensitivity, and resting energy expenditure with no change in body weight or fat mass (O'Mara et al., J Clin Invest 2020, PMID 31961826)—an open-label study without placebo control. Rat studies confirmed selective β3-adrenoceptor agonist activity with bladder-relaxant effects (Hatanaka et al., 2013, PMID 23239087). Ex vivo porcine ureter studies found mirabegron reduced contractility partly via α1-adrenoceptor antagonism, complicating a pure β3-selectivity profile at the ureter (PMC9192402).