Agents for treatment of overactive bladder: a therapeutic class review.

Overactive bladder (OAB) is a medical syndrome defined by symptoms of urgency, with or without urge urinary incontinence (any involuntary loss of urine), usually with frequency and nocturia. Although anticholinergic agents have been the first-line treatment for OAB for many years, the efficacious pharmacologic management of this condition has been compromised by concerns regarding tolerability. Flavoxate was the first anticholinergic and antispasmodic agent approved by the Food and Drug Administration (FDA) to treat symptoms of OAB but is not routinely used today since newer agents are more effective. The more recent drugs, oxybutynin and tolterodine, have appeared to be equally efficacious in treating the symptoms of OAB in clinical trials; however, tolterodine has proven to be better tolerated with fewer adverse effects. In 2004, the FDA approved the three newest agents for the class: darifenacin, solifenacin, and trospium. Compared with oxybutynin and tolterodine, these agents have a more favorable side effect profile, which can enhance tolerability and patient compliance. Side effects are reduced in part because of the drugs' greater tissue selectivity for inhibiting the bladder muscle contraction over other anticholinergic receptors in the body. In recent clinical trials, darifenacin, solifenacin, and trospium have shown superiority to placebo and efficacy comparable to that of oxybutynin and tolterodine.