Does solifenacin cross the blood-brain barrier?

Solifenacin crosses the blood-brain barrier to a limited extent. As a muscarinic receptor antagonist used to treat overactive bladder, solifenacin is designed with a quaternary ammonium structure that reduces its ability to penetrate the blood-brain barrier compared to older anticholinergic medications. However, it is not completely excluded from the central nervous system. This limited penetration explains why solifenacin typically causes fewer central nervous system side effects (such as confusion, memory problems, or cognitive impairment) than older anticholinergic drugs, particularly in elderly patients. Despite this relative advantage, some patients may still experience central effects, especially at higher doses or in those with compromised blood-brain barrier integrity, such as elderly patients or those with certain neurological conditions. When prescribing solifenacin (typically at doses of 5-10 mg daily), clinicians should monitor for potential cognitive effects, particularly in vulnerable populations, even though these effects are less common than with other anticholinergics.