Darifenacin is a potent, competitive and selective muscarinic receptor antagonist which 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 increase bladder capacity.

Darifenacin is indicated for the treatment of overactive bladder with symptoms of urge urinary incontinence, urgency and frequency.

Darifenacin 7.5 mg once daily; may increase dose to 15 mg once daily if no adequate response after 2 wk of therapy. Darifenacin should be taken with liquid. It can be taken with or without food, and should be swallowed whole and not chewed, divided or crushed.

For patients with moderate hepatic impairment or when co-administered with potent CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, ritonavir, nelfinavir, clarithromycin and nefazadone), the daily dose of Darifenacin should not exceed 7.5 mg.

Patient with urinary retention, gastric retention, uncontrolled narrow-angle glaucoma, and in patients who are at risk for these conditions.

The most common side effects are dry mouth & constipation. Other less commonly reported side effects include- abnormal vision, back pain, dry skin, hypertension, vomiting, peripheral edema, weight gain, arthralgia, bronchitis, pharyngitis, rhinitis, sinusitis, rash, pruritus, urinary tract disorder and vaginitis.

Overdose Effects

Overdosage with antimuscarinic agents can result in severe antimuscarinic effects. ECG monitoring is recommended when event of overdosage is occurred. Darifenacin has been administered in clinical trials at doses up to 75 mg (five times the maximum therapeutic dose) and signs of overdose were limited to abnormal vision.

Darifenacin should be used with caution in the patient at risk for urinary retention & decreased gastrointestinal motility, with impaired renal & hepatic impairment.

Pregnancy & Lactation

Pregnancy Category C. Darifenacin should be used during pregnancy only if the benefit to the mother outweighs the potential risk to the fetus.

Lactation: It is not known whether Darifenacin is excreted into human milk and therefore caution should be exercised before Darifenacin is administered to a nursing woman.