Also available in 1 mL, 5 mg, 10 mg, 50 mg, 100 mg, 500 mg and bulk. Please contact Fisher for quotes. Fesoterodine fumarate (Toviaz) is the fumarate salt form of fesoterodine, a competitive muscarinic receptor antagonist with muscle relaxant and urinary antispasmodic properties. Fesoterodine is rapidly hydrolyzed in vivo into its active metabolite 5-hydroxymethyl tolterodine, which binds and inhibits muscarinic receptors on the bladder detrusor muscle, thereby preventing bladder contractions or spasms caused by acetylcholine. Purity 98.55%