Solifenacin

INTRODUCTION

Indications

Overactive bladder with symptoms (urge incontinence, urgency, frequency).

Action

Acts as a muscarinic (cholinergic) receptor antagonist; antagonizes bladder smooth muscle contraction. Therapeutic Effects: Decreased symptoms of overactive bladder.

Adverse Reactions/Side Effects

EENT: blurred vision. GI: constipation, dry mouth, dyspepsia, nausea.

PHYSICAL THERAPY IMPLICATIONS

Examination and Evaluation

• Monitor signs of urine retention (difficult urination, painful or distended abdomen). Excessive urinary retention may require dose adjustment by physician.

Interventions

• When appropriate, implement pelvic floor muscle–strengthening activities and other therapeutic exercises to help maintain bladder control.

Patient/Client-Related Instruction

• Advise patient to increase fluid intake and dietary fiber to avoid constipation. Laxatives may also be helpful in patients susceptible to fecal impaction.

• Instruct patient and family/caregivers to report other troublesome side effects such as severe or prolonged blurred vision or GI problems (nausea, dry mouth, indigestion).

Pharmacokinetics

Absorption: Well absorbed (90%).

Distribution: Unknown.

Protein Binding: 98%.

Metabolism and Excretion: Extensively metabolized by the CYP3A4 enzyme system. 69% excreted in urine as metabolites, 22% in feces.

Half-life: 45–68 hr.

Contraindications/Precautions

Contraindicated in: Hypersensitivity; Urinary retention; Gastric retention; Uncontrolled angle-closure glaucoma; Severe hepatic impairment; Lactation.

Use Cautiously in: Concurrent use of CYP3A4 inhibitors (use lower dose/clinical monitoring may be necessary); Moderate hepatic impairment (lower dose recommended); Renal impairment (dose should not exceed 5 mg/day if CCr < 30 mL/min); Bladder outflow obstruction; GI obstructive disorders, severe constipation or ulcerative colitis; Myasthenia gravis; Angle-closure glaucoma; Children (safety not established); Pregnancy (use only if maternal benefit outweighs fetal risk).

Interactions

Drug-Drug: Drugs that induce or inhibit the CYP3A4 enzyme system may significantly alter blood levels of solifenacin; ketoconazole ↑ blood levels and risk of toxicity (do not exceed 5 mg/day).

Route/Dosage

PO (Adults): 5 mg once daily, may be ↑ to 10 mg once daily; hepatic impairment/severe renal impairment, concurrent use of ketoconazole or other inhibitors of CYP3A4—dose should not exceed 5 mg/day.

Availability

Tablets: 5 mg, 10 mg.