Table 2.

Clinical properties of topical anticholinergics

Agent	Clinical properties	Absorption	Long-term use concern	Trials assessing concern
Glycopyrronium tosylate (GT)	Permanently charged quaternary amine therefore minimizes oral bioavailability and blood–brain barrier permeability. [35] The diffusion of the active drug is insufficient for the induction of the systemic response, which significantly reduces the possible adverse reactions. [9] In particular, CNS-related adverse effects [36]	Minimal	None	A safety analysis showed no phototoxic, genotoxic, or carcinogenic effect [9]
Oxybutynin	Tertiary amine structure provides ability to cross the blood–brain barrier given its lipophilic nature [34]	Moderate	Neurotoxicity (dementia should be considered)	None
Sofpironium bromide	Similar in chemical structure to glycopyrronium bromide. It has a high binding affinity for the M3 cholinergic receptor at the local site of administration, but is hydrolyzed at the ester linkage to less active metabolites upon entry into blood [31]	Minimal	Unknown	Phase II and III studies completed, currently approved in Japan
Umeclidinium (UMEC)	Long-acting muscarinic antagonist with minimal ability to cross the blood–brain barrier	Minimal	Unknown	Limited studies, one phase II and III study