An M1 muscarinic acetylcholine receptor antagonist (Ki = 0.59 nM in rat brain membranes); selective for M1 receptors over the serotonin transporter (Ki = 5,150 nM); binds to the dopamine transporter and inhibits dopamine reuptake (Kis = 237 and 130 nM, respectively); inhibits acid sphingomyelinase by 87% at 10 mM