Vibegron

Overactive bladder is characterized by symptoms of urge urinary incontinence, urgency, and urinary frequency. Bladder filling and emptying are regulated by the coordinated communication between sympathetic and parasympathetic systems. Bladder filling occurs via parasympathetic inhibition and the sympathetic hypogastric nerve releasing norepinephrine, which acts on beta-adrenergic receptors responsible for mediating detrusor muscle relaxation. Symptoms of overactive bladder are thought to be caused by the deterioration of the sensory connections between the bladder, spinal cord and brain, leading to changes in the lower urinary tract and abnormal bladder sensations of the urge to void at small bladder volumes.

Beta-3 adrenergic receptors (β3ARs) are expressed in the kidneys and lower urinary tract, including ureters, urethra, prostate, and bladder. Vibegron is a selective agonist at β3AR. One vibegron binds to the receptor, β3AR is stimulated and undergoes a conformation change and activates adenylyl cyclases (AC), which promotes the formation of cyclic adenosine monophosphate (cAMP). Increased intracellular cAMP concentration leads to the activation of cAMP-dependent protein kinase A (PKA), which subsequently phosphorylates myosin light chains that are responsible for inhibiting the interaction of actin with myosin dependent on calcium – calmodulin complex. In clinical trials, vibegron increased cAMP levels in a dose-proportional manner. There is evidence that β3AR agonists may also work via sensory mechanisms without directly affecting detrusor muscle motor function.