Solifenacin

• Overactive Bladder
• Urge Incontinence
• Urinary Frequency
• Urinary Urgency

Solifenacin is an antimuscarinic (anticholinergic) medication used to treat overactive bladder (OAB) with symptoms of urge urinary incontinence, urgency, and urinary frequency. It offers once-daily dosing and selectivity for the M3 muscarinic receptor.

Mechanism of Action

Solifenacin works through muscarinic receptor antagonism:

• M3 receptor selectivity: Greater affinity for M3 than M2 muscarinic receptors
• Bladder smooth muscle relaxation: M3 receptors mediate detrusor muscle contraction
• Reduces involuntary contractions: Decreases detrusor overactivity during filling phase
• Increases bladder capacity: Allows greater urine storage before urgency
• Long half-life: Enables once-daily dosing

Available Formulations

Solifenacin is available as film-coated tablets:

• 5 mg tablets
• 10 mg tablets

Also available in combination with mirabegron (Vibegron).

Medical Uses

FDA-Approved Indication:

• Treatment of overactive bladder with symptoms of urge urinary incontinence, urgency, and urinary frequency

Dosing Guidelines

Adults:

• Starting dose: 5 mg once daily
• May increase to 10 mg once daily if needed
• Swallow tablets whole with liquids

Renal Impairment (CrCl <30 mL/min):

• Do not exceed 5 mg daily

Hepatic Impairment:

• Moderate (Child-Pugh B): Do not exceed 5 mg daily
• Severe (Child-Pugh C): Not recommended

With Strong CYP3A4 Inhibitors:

• Do not exceed 5 mg daily

Important Safety Information

Contraindications:

• Urinary retention
• Gastric retention
• Uncontrolled narrow-angle glaucoma
• Known hypersensitivity to solifenacin

Warnings and Precautions:

• Angioedema: Discontinue immediately if occurs
• Central nervous system effects: Somnolence, hallucinations reported
• QT prolongation: Use with caution in patients at risk
• Decreased gastric motility: Use with caution in severe constipation or GI obstruction
• Controlled narrow-angle glaucoma: Use with caution
• Hepatic and renal impairment: Dose adjustment required
• Cognitive effects: May impair ability to drive; particularly concerning in elderly

Drug Interactions

Strong CYP3A4 Inhibitors (ketoconazole, clarithromycin, ritonavir):

• Limit solifenacin to 5 mg daily

CYP3A4 Inducers (rifampin):

• May reduce solifenacin efficacy; no specific recommendation

Other Anticholinergics:

• Additive anticholinergic effects; use caution

Cholinesterase Inhibitors:

• Antagonistic effects; avoid combination if possible

QT-Prolonging Drugs:

• Use with caution; additive effects possible

Special Populations

• Hepatic Impairment:
  • Moderate: Max 5 mg daily
  • Severe: Not recommended
• Renal Impairment (CrCl <30): Max 5 mg daily
• Elderly: Use with caution; higher sensitivity to anticholinergic effects
• Pregnancy: Limited data; use only if benefit outweighs risk
• Lactation: Unknown if excreted in milk
• Pediatric: Safety not established; not recommended