ATC Group: G04BD Urinary antispasmodics

Darifenacin is a selective muscarinic M3 receptor antagonist (M3 SRA) in vitro. The M3 receptor is the major subtype that controls urinary bladder muscle contraction. It is not known whether this selectivity for the M3 receptor translates into any clinical advantage when treating symptoms of overactive bladder syndrome.

Desfesoterodine is a competitive, specific muscarinic receptor antagonist. It is the primary active metabolite of fesoterodine, and regarded as main active pharmacological principle of fesoterodine; fesoterodine is considered as prodrug of desfesoterodine. The affinity of desfesoterodine for the muscarinic receptors is 2 orders of magnitude greater than that of fesoterodine.

Fesoterodine is a competitive, specific muscarinic receptor antagonist. It is rapidly and extensively hydrolysed by non-specific plasma esterases to the 5-hydroxymethyl derivative, its primary active metabolite, which is the main active pharmacological principle of fesoterodine.

Flavoxate is an antispasmodic selective to the urinary tract. Flavoxate has been shown to have a direct antispasmodic action on smooth muscle fibres.

Imidafenacin is an antagonist of muscarinic cholinergic receptors and used for treatments of overactive bladder. Imidafenacin antagonizes subtypes M3 and M1 in vitro. In the urinary bladder, imidafenacin inhibits acetylcholine release by antagonizing subtype M1 and contraction of smooth muscles by antagonizing subtype M3. Compared with the inhibitory effect on the salivary gland, imidafenacin shows higher inhibitory effect on the urinary bladder contraction, probably indicating efficacy and safety of these products in the clinical practice.

Mirabegron is a potent and selective beta₃-adrenoceptor agonist. Mirabegron enhances urine storage function by stimulating beta₃-adrenoceptors in the bladder.

Oxybutynin acts as a competitive antagonist of acetylcholine at post-ganglionic muscarinic receptors, resulting in relaxation of bladder smooth muscle.

Propiverine inhibits calcium influx and modulates intracellular calcium in urinary bladder smooth muscle cells causing musculotropic spasmolysis. Also, it inhibits the efferent connection of the nervus pelvicus due to anticholinergic action.

Solifenacin is a competitive, specific cholinergic-receptor antagonist. In vitro and in vivo pharmacological studies indicate that solifenacin is a competitive inhibitor of the muscarinic M3 subtype receptor.

Tolterodine is a competitive, specific muscarinic receptor antagonist with selectivity for the urinary bladder over salivary glands in vivo.

Trospium is an antispasmodic, antimuscarinic agent indicated for the treatment of overactive bladder with symptoms of urge urinary incontinence, urgency, and urinary frequency. Receptor assays showed that trospium has negligible affinity for nicotinic receptors as compared to muscarinic receptors at concentrations obtained from therapeutic doses. Trospium antagonizes the effect of acetylcholine on muscarinic receptors in cholinergically innervated organs. Its parasympatholytic action reduces the tonus of smooth muscle in the bladder.

Vibegron is a selective and potent human beta-3 adrenergic receptor agonist over β1-AR and β2-AR. Activation of the beta-3 adrenergic receptor located in the bladder detrusor muscle increases bladder capacity by relaxing the detrusor smooth muscle during bladder filling.