What class of medication is solifenacin?

Solifenacin Drug Classification

Solifenacin is classified as a muscarinic receptor antagonist (antimuscarinic) medication used primarily for the treatment of overactive bladder. 1

Pharmacological Classification Details

• Solifenacin is specifically a muscarinic antagonist that acts on M1 and M3 receptor subtypes 2
• It functions as a competitive antagonist at muscarinic acetylcholine receptors, blocking the binding of acetylcholine to these receptors 1
• The drug is marketed as solifenacin succinate, a tertiary amine with anticholinergic properties 3

Mechanism of Action

• Solifenacin works by inhibiting contraction of the smooth muscle wall surrounding the bladder 4
• It has greater selectivity for bladder muscarinic receptors compared to salivary gland receptors, which may contribute to its tolerability profile 2
• Normal micturition occurs following stimulation of acetylcholine muscarinic M3 receptors within the detrusor muscle wall; solifenacin blocks this action 4

Clinical Applications

• FDA-approved for the treatment of adults with overactive bladder with symptoms of urge urinary incontinence, urgency, and urinary frequency 1
• Used in combination therapy with tamsulosin for men with both storage and voiding lower urinary tract symptoms 5
• European Association of Urology guidelines recognize solifenacin as an effective antimuscarinic agent for treating storage symptoms in patients with lower urinary tract symptoms 5
• May be used in combination therapy with β3-adrenoceptor agonists (like mirabegron) for patients refractory to monotherapy 6

Pharmacokinetic Properties

• High absolute bioavailability of approximately 90% 3
• Peak plasma concentrations reached 3-8 hours after oral administration 3
• Terminal elimination half-life ranges from 33 to 85 hours, allowing for once-daily dosing 3
• Primarily metabolized via hepatic cytochrome P450 (CYP) 3A4 3
• Only about 7% of the dose is excreted unchanged in urine 3

Dosage Considerations

• Standard dosing is 5 mg tablet taken orally once daily, which may be increased to 10 mg once daily if well tolerated 1
• Dose should not exceed 5 mg in patients with:
  • Severe renal impairment (creatinine clearance <30 mL/min) 1
  • Moderate hepatic impairment (Child-Pugh B) 1
  • Concomitant use of strong CYP3A4 inhibitors 1, 3

Clinical Efficacy

• Solifenacin has demonstrated efficacy in reducing overactive bladder symptoms including frequency, urgency, and incontinence episodes 7
• In clinical trials, solifenacin showed at least equal efficacy to extended-release tolterodine in reducing micturition frequency and urgency episodes 3, 8
• Approximately 53% of patients with incontinence at baseline achieved complete continence with solifenacin treatment 7

Common Side Effects

• Most common adverse reactions are anticholinergic in nature:
  • Dry mouth (most common) 7
  • Constipation 7
  • Blurred vision 7
• Most adverse events are mild to moderate in intensity 7

Important Contraindications

• Urinary retention 1
• Gastric retention 1
• Uncontrolled narrow-angle glaucoma 1
• Hypersensitivity to solifenacin or any component of the formulation 1