Darifenacin

Key facts

• Darifenacin (sold as Enablex or Emselex) is an antimuscarinic that relaxes the bladder muscle. It treats overactive bladder: urgency, frequent urination and urge incontinence.
• Taken as one tablet daily, swallowed whole; symptom improvement builds over several weeks.
• It must not be used by people with urinary retention, significant gastric retention, or uncontrolled narrow-angle glaucoma, since blocking these nerve signals can make all three dangerously worse.
• Seek urgent care for an inability to pass urine, severe eye pain with halos around lights, or facial or throat swelling with difficulty breathing.

What darifenacin treats

Darifenacin treats overactive bladder syndrome, a condition where the bladder muscle contracts involuntarily and causes urinary urgency, increased daytime and nighttime frequency, and urge incontinence (leakage before reaching a toilet). It does not treat stress incontinence, the leakage caused by coughing, laughing or exercise, and it does not treat bladder infections.

How darifenacin works

The bladder wall muscle contracts when a signalling chemical, acetylcholine, binds to M3 muscarinic receptors on it. Darifenacin selectively blocks these M3 receptors, letting the muscle relax and hold more urine before it signals the urge to void.

Before you take it

• Do not take darifenacin if you have urinary retention, severe constipation or bowel obstruction, or uncontrolled narrow-angle glaucoma.
• Tell your prescriber about myasthenia gravis, liver disease, or an enlarged prostate that already causes urinary blockage.
• Other anticholinergic drugs, including some antihistamines, antidepressants and antipsychotics, add to dry mouth and constipation; strong CYP3A4 inhibitors such as ketoconazole or ritonavir raise darifenacin levels and may require a lower dose.
• Older adults are more sensitive to confusion and constipation from anticholinergic medicines.

Side effects

Common effects include dry mouth, constipation, blurred vision, headache, and a feeling that the bladder has not fully emptied.

Stop and seek urgent medical care for any of these:

• Complete inability to pass urine.
• Severe abdominal pain and bloating, or no bowel movement for several days.
• Eye pain with halos around lights or sudden vision changes.
• Facial or throat swelling with difficulty breathing.

Safety essentials

• Untreated urinary retention, bowel obstruction, and uncontrolled narrow-angle glaucoma are absolute contraindications, not cautions to weigh; darifenacin can turn each into a medical emergency.
• Treat constipation early with fluids and fibre. Severe, unresolved constipation on anticholinergic drugs has progressed to bowel obstruction.
• New confusion, memory problems or drowsiness in an older adult may signal building anticholinergic effects; report this rather than adding another anticholinergic medicine.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.