Oxybutynin-d₁₀is intended for use as an internal standard for the quantification of oxybutynin by GC- or LC-MS. Oxybutynin is an antagonist of muscarinic acetylcholine receptors (K_is = 5, 14.5, 3.7, 5.3, and 40 nM for human recombinant M_1-5, respectively).¹It inhibits intracellular calcium mobilization induced by carbamoylcholine in bladder smooth muscle and submandibular gland cells isolated from cynomolgus monkeys (K_is = 2 and 1 nM, respectively).²Oxybutynin inhibits volume-induced bladder contraction (VIBC) and oxotremorine-induced salivation (OIS) in rats (ID₅₀s = 0.062 and 0.089 mg/kg, respectively).¹It also increases pupil diameter (PD) and locomotor activity (LMA; ED₅₀s = 0.29 and 0.52 mg/kg, respectively) and decreases small intestinal transit (SIT; ID₅₀= 0.22 mg/kg) in rats. Formulations containing oxybutynin have been used in the treatment of overactive bladder.

1.McNamara, A., Pulido-Rios, M.T., Sweazey, S., et al.Pharmacological properties of TD-6301, a novel bladder selective muscarinic receptor antagonistEur. J. Pharmacol.605(1-3)145-152(2009) 2.Kobayashi, S., Ikeda, K., and Miyata, K.Comparison of in vitro selectivity profiles of solifenacin succinate (YM905) and current antimuscarinic drugs in bladder and salivary glands: A Ca2+ mobilization study in monkey cellsLife Sci.74(7)843-853(2004)