Darifenacin is a potent, competitive, and selective muscarinic receptor antagonist that has greater binding affinity for muscarinic M3 receptors. M3 receptors are involved in the contraction of the detrusor muscle of the bladder, GI smooth muscle, saliva production, and iris sphincter function.
Darifenacin may increase volume threshold in patients with involuntary detrusor contraction, thus increasing bladder capacity.

Adult
PO
Overactive bladder. For symptomatic treatment of urge incontinence, urinary frequency and urgency. Initial: 7.5 mg once daily; may increase dose to 15 mg once daily if no adequate response after 2 wk of therapy.

Hepatic impairment. Moderate hepatic impairment (Child Pugh B): maximum daily dose is 7.5 mg. Severe hepatic impairment (Child Pugh C): not recommended.
Special populations: patient receiving concomitant treatment with ketoconazole, itraconazole, ritonavir, nelfinavir, clarithromycin, nefazodone: maximum daily dose is 7.5 mg.

Adverse drug reactions: dry mouth, nausea, abdominal pain, constipation, diarrhea, dyspepsia, dizziness, headache, dry skin, rash, pruritus, dry eyes, abnormal vision, arthralgia, bronchitis, pharyngitis, rhinitis, sinusitis, flu-like syndrome, vaginitis, acute urinary retention, hypertension, and peripheral edema.

CIMS Drug Information System. Internet. Accessed on January 10, 2016.