Although the mechanism of action of antimuscarinic agents used for the treatment of overactive bladder (such as oxybutynin and tolterodine) is thought to be due mainly to suppression of detrusor contraction through blockade of M3 muscarinic receptors on detrusor smooth muscle, an effect on central muscarinic receptors, located in the brain cannot be ruled out as both compounds pass into the central nervous system [32]. The gene discussed is CHRM3; the disease is overactive bladder.