| Anticholinergic adverse effects | Darifenacin (Enablex), solifenacin (Vesicare), tolterodine ER (Detrol LA), oxybutynin ER (Ditropan XL) | ER products and drugs with uroselectivity may offer enhanced tolerability. | 15,27,31 |
| CNS adverse effects | Trospium (Sanctura) | Trospium may be less likely to cross the blood-brain barrier (unproven benefit). | 31 |
| Cost | Oxybutynin IR | ER and newer agents may be more expensive; generics are available for oxybutynin IR. | 22 |
| Drug-drug interactions | Trospium | Agents other than trospium are metabolized by CYP 3A4 or 2D6, which are responsible for elimination of hepatically metabolized drugs.* | 9 |
| Effectiveness | Oxybutynin | Nonselectivity may offer more complete suppression of detrusor overactivity. Head-to-head studies of tolterodine and oxybutynin have suggested improved efficacy with oxybutynin. | 27 |
| Pregnancy | Oxybutynin | Oxybutynin is pregnancy risk category B whereas all other agents are class C. | 2 |
| Severe hepatic impairment | Trospium | Trospium is eliminated renally whereas all other agents undergo extensive hepatic metabolism.* | 5,16,22,35 |
| Severe renal impairment | Oxybutynin, tolterodine, darifenacin, solifenacin | Avoid trospium because it is eliminated renally. | 9 |