Solifen

• Overactive Bladder (OAB) with Symptoms of Urgency, Frequency, and Urge Incontinence:
  Approved for treatment of patients experiencing OAB symptoms, including urinary urgency, increased frequency, and urge urinary incontinence.
• Neurogenic Bladder Dysfunction (Off-label use):
  Sometimes used in patients with neurogenic detrusor overactivity under specialist supervision.

Adults:

• Initial dose: 5 mg orally once daily, with or without food.
• Based on clinical response and tolerability, dose may be increased to 10 mg once daily after 1–2 weeks.

Elderly:

• Start with 5 mg once daily; dose increase to 10 mg should be approached cautiously due to increased risk of adverse effects.

Pediatrics:

• Safety and efficacy not established; generally not recommended.

Renal Impairment:

• Mild to moderate impairment: no dose adjustment necessary.
• Severe impairment (creatinine clearance <30 mL/min): use with caution; maximum dose 5 mg daily.

Hepatic Impairment:

• Mild to moderate impairment: no dose adjustment necessary.
• Severe hepatic impairment: use contraindicated.

Solifenacin succinate is a competitive muscarinic receptor antagonist, with selectivity for the M3 receptor subtype found in the bladder detrusor muscle. By blocking M3 receptors, it inhibits acetylcholine-induced bladder muscle contractions, thereby reducing involuntary detrusor contractions, urinary urgency, frequency, and incontinence. This action leads to increased bladder capacity and decreased symptoms of overactive bladder.

• Absorption: Rapidly absorbed with peak plasma concentration reached within 3–8 hours.
• Bioavailability: Approximately 90%.
• Distribution: High plasma protein binding (~98%).
• Metabolism: Primarily hepatic via CYP3A4 to inactive metabolites.
• Half-life: Approximately 45–68 hours, allowing once-daily dosing.
• Elimination: Mainly excreted via feces (69%) and urine (23%).

• Pregnancy: No adequate and well-controlled studies in pregnant women; use only if potential benefit justifies potential risk. Classified as Pregnancy Category C.
• Lactation: Unknown if excreted in human milk; caution advised. Consider risk-benefit before administration to breastfeeding mothers.

• Primary Therapeutic Class: Antimuscarinic agent
• Subclass: Selective M3 muscarinic receptor antagonist

• Known hypersensitivity to solifenacin or any excipients
• Urinary retention
• Gastric retention
• Uncontrolled narrow-angle glaucoma
• Severe hepatic impairment

• Use with caution in patients with conditions that may be worsened by anticholinergic effects (e.g., gastrointestinal obstructive disorders, myasthenia gravis, severe ulcerative colitis).
• Monitor for signs of urinary retention, especially in patients with bladder outlet obstruction.
• Caution in patients with QT prolongation or on drugs that prolong QT interval.
• Avoid use in severe hepatic impairment.
• Elderly patients may be more sensitive to anticholinergic adverse effects.

Common Adverse Effects:

• Dry mouth
• Constipation
• Blurred vision
• Dry eyes
• Dyspepsia

Serious/Rare Side Effects:

• Urinary retention
• Angioedema
• QT prolongation (rare)
• Increased intraocular pressure (glaucoma exacerbation)

Timing & Severity:

• Most side effects appear early during treatment and tend to be mild to moderate; constipation and dry mouth are dose-related.

• CYP3A4 Inhibitors (e.g., ketoconazole, clarithromycin): May increase solifenacin plasma levels; use caution or dose adjustment.
• Other Anticholinergic Drugs: May increase anticholinergic side effects.
• Drugs prolonging QT interval: Caution due to additive effects on QT prolongation.
• P-glycoprotein substrates: Potential interaction but clinical significance is minimal.

• Current clinical guidelines maintain solifenacin as a first-line oral treatment for OAB due to favorable efficacy and tolerability.
• Recent safety warnings emphasize caution with QT prolongation risks in patients on concurrent QT-prolonging drugs.
• Updated renal and hepatic dosing recommendations to improve safety in special populations.

• Store at controlled room temperature between 20°C to 25°C (68°F to 77°F).
• Protect from moisture and light.
• Keep out of reach of children.
• No refrigeration or special handling required.