Competitively antagonizes muscarinic receptors, reducing contractions of urinary bladder smooth muscle
Tablets (extended-release): 7.5 mg, 15 mg
Indications and dosages
➣ Overactive bladder with symptoms of urge urinary incontinence, urgency, and frequency
Adults: Initially, 7.5 mg P.O. daily; may increase to 15 mg P.O. daily as early as 2 weeks after therapy begins
• Moderate hepatic impairment
• Concurrent use of potent CYP3A4 inhibitors (such as clarithromycin, itraconazole, ketoconazole, nefazodone, nelfinavir, and ritonavir)
• Hypersensitivity to drug or its components
• Urinary retention, gastric retention, uncontrolled angle-closure glaucoma, or increased risk for these conditions
Use cautiously in:
• decreased GI motility (such as severe constipation, ulcerative colitis, or myasthenia gravis), controlled angleclosure glaucoma, hepatic impairment
• pregnant or breastfeeding patients
• children (safety and efficacy not established).
• Administer tablets whole with liquid (with or without food) once daily.
• Make sure patient doesn't chew, crush, or divide them.
• Know that drug isn't recommended for patients with severe hepatic impairment.
CNS: dizziness, asthenia
EENT: dry eyes, abnormal vision, dry throat, bronchitis, pharyngitis, rhinitis, sinusitis
GI: nausea, vomiting, diarrhea, constipation, abdominal pain, dyspepsia, dry mouth
GU: urinary tract infection or disorder, vaginitis
Musculoskeletal: back pain, arthralgia
Skin: dry skin, rash, pruritus
Other: abnormal taste, weight gain, accidental injury, flulike syndrome, pain, peripheral edema, heat prostration
Drug-drug. Anticholinergics: increased frequency or severity of adverse reactions
CYP4502D6 inhibitors: increased darifenacin exposure and blood level
Drugs metabolized by CYP2D6 (such as flecainide, thioridazine, and tricyclic antidepressants): increased blood levels of these drugs
• Monitor liver function tests frequently; withdraw drug if liver function tests show severe hepatic impairment.
• Monitor urinary function periodically.
• Instruct patient to take tablets whole with liquid, with or without food. Tell him not to chew, divide, or crush them.
• Inform patient that some over-the-counter products such as antihistamines may increase risk of side effects.
• Caution patient that drug may cause heat prostration; describe signs and symptoms.
• As appropriate, review all other significant adverse reactions and interactions, especially those related to the drugs mentioned above.