Antimuscarinic (M3-selective) Pregnancy: Not recommended during pregnancy — there is a limited amount of data in pregnant women and animal studies have shown toxicity to parturition. Breast-feeding: it is not known whether darifenacin is excreted in human milk (it is excreted in rat milk); a risk to the nursing child cannot be excluded, so the decision should be based on a benefit/risk comparison. Fertility: no human fertility data — women of child-bearing potential should be made aware of this (SPC §4.6).

Darifenacin

Brand names: Emselex

Darifenacin is an antimuscarinic agent used to treat the symptoms of overactive bladder, including urinary frequency, urgency and urge incontinence.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 7.5 mg once daily initially; may be increased to 15 mg once daily (prolonged-release tablets)

Route: Oral

Frequency: Once daily

UK SPC (Darifenacin 15 mg prolonged-release tablets) §4.2: adults — the recommended starting dose is 7.5 mg daily. After 2 weeks of starting therapy, patients should be reassessed; for those requiring greater symptom relief the dose may be increased to 15 mg daily, based on individual response. Elderly (≥65 years): the recommended starting dose is also 7.5 mg daily, reassessed for efficacy and safety after 2 weeks, then increased to 15 mg daily in those with an acceptable tolerability profile who require greater symptom relief. Only the 7.5 mg and 15 mg once-daily doses are described in the SPC — no higher dose is given. Hepatic impairment: no adjustment in mild impairment (Child Pugh A), though there is a risk of increased exposure; moderate impairment (Child Pugh B) — treat only if benefit outweighs risk and restrict the dose to 7.5 mg daily; contraindicated in severe impairment (Child Pugh C). With potent CYP2D6 inhibitors (paroxetine, terbinafine, quinidine, cimetidine) or moderate CYP3A4 inhibitors (fluconazole, grapefruit juice, erythromycin), start at 7.5 mg daily; the dose may be titrated to 15 mg daily to obtain an improved clinical response provided it is well tolerated, but caution should be exercised. Method of administration: taken once daily with liquid, with or without food; must be swallowed whole and not chewed, divided or crushed. Paediatric: not recommended for use in children below 18 years of age due to a lack of data on safety and efficacy.

Dose adjustments

Renal

No dose adjustment is required in patients with impaired renal function; however, caution should be exercised when treating this population (SPC §4.2).

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to darifenacin or to any of the excipients
Urinary retention
Gastric retention
Uncontrolled narrow-angle glaucoma
Myasthenia gravis
Severe hepatic impairment (Child Pugh C)
Severe ulcerative colitis
Toxic megacolon
Concomitant treatment with potent CYP3A4 inhibitors

Side effects

Dry mouth (very common — 20.2% at 7.5 mg and 35% at 15 mg; 8–9% with placebo)
Constipation (very common — 14.8% at 7.5 mg and 21% at 15 mg; 5.4–7.9% with placebo)
Headache (common)
Dry eye and nasal dryness (common)
Abdominal pain, nausea, dyspepsia (common)
Urinary retention, urinary tract disorder, bladder pain (uncommon); generalised hypersensitivity reactions including angioedema (not known)

Interactions

Potent CYP3A4 inhibitors (protease inhibitors such as ritonavir, ketoconazole, itraconazole) — contraindicated; co-administration of darifenacin 7.5 mg with ketoconazole 400 mg gave a 5-fold increase in steady-state darifenacin AUC (about 10-fold in poor metabolisers)
Potent P-glycoprotein inhibitors such as ciclosporin and verapamil — should also be avoided
Moderate CYP3A4 inhibitors (erythromycin, clarithromycin, telithromycin, fluconazole, grapefruit juice) — start at 7.5 mg daily, titrate to 15 mg only if well tolerated, with caution
Potent CYP2D6 inhibitors (paroxetine, terbinafine, cimetidine, quinidine) — start at 7.5 mg daily; exposure increases (e.g. by 33% with paroxetine 20 mg at the 30 mg darifenacin dose)
Other anticholinergic/antimuscarinic agents — may increase the frequency and/or severity of dry mouth, constipation, blurred vision and other anticholinergic effects (US PI §7.3)
Medicines predominantly metabolised by CYP2D6 with a narrow therapeutic window (flecainide, thioridazine, tricyclic antidepressants) — use with caution (US PI §7.2)

Clinical monograph

How it works

It selectively antagonises M3 muscarinic receptors on the detrusor muscle, reducing involuntary bladder contractions and increasing functional bladder capacity.

Prescribing in practice

It is contraindicated in urinary retention, significant gastric outflow obstruction and uncontrolled narrow-angle glaucoma because of antimuscarinic effects.
Dry mouth and constipation are the most common adverse effects and may limit tolerability.
Dose adjustment and caution are needed with potent CYP3A4 inhibitors and in hepatic impairment.

Monitoring

Monitor symptomatic response and antimuscarinic adverse effects, reassessing the need for continued treatment periodically.

Counselling the patient

Swallow the tablet whole and expect benefit to build over a few weeks.
Dry mouth and constipation are common; maintaining fluids and fibre can help.
Report difficulty passing urine or new eye pain and visual disturbance.

Evidence & guidelines

NICE guidance on urinary incontinence supports antimuscarinics such as darifenacin for overactive bladder when conservative measures are insufficient.

Reference: NICE NG123; BAUS / EAU; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Drugs

Solifenacin succinate · Antimuscarinic (M3-selective)

Pathways