Action

Antagonizes effects of acetylcholine on muscarinic receptors in cholinergically innervated organs, reducing bladder smooth muscle tone

Availability

Capsules (extended-release): 60 mg

Tablets: 20 mg

Indications and dosages

➣ Overactive bladder with symptoms of urge urinary incontinence, urgency, and urinary frequency

Adults: 20 mg P.O. twice daily 1 hour before meals or on empty stomach, or 1 60-mg capsule daily in morning with water at least 1 hour before a meal

Dosage adjustment

• Severe renal impairment

• Patients age 75 and older

Contraindications

• Hypersensitivity to drug or its components

• Preexisting or risk of urinary or gastric retention or uncontrolled angle-closure glaucoma

Precautions

Use cautiously in:

• moderate renal impairment, moderate to severe hepatic impairment, decreased GI motility, controlled angle-closure glaucoma, clinically significant bladder outflow obstruction or GI obstructive disorders

• patients at risk for heat prostration

• elderly patients

• pregnant or breastfeeding patients

• children (safety and efficacy not established).

Administration

• Give at least 1 hour before meals or on empty stomach.

Adverse reactions

CNS: headache, fatigue, syncope, hallucinations, delirium, dizziness, drowsiness

CV: tachycardia, chest pain

EENT: dry eyes, blurred vision, dry throat

GI: vomiting, constipation (new-onset or aggravated), upper abdominal pain, dyspepsia, flatulence, abdominal distention, dry mouth

GU: urinary retention

Skin: dry skin

Other: altered taste, heat prostration, angioedema

Interactions

Drug-drug. Anticholinergics: additive anticholinergic effects

Digoxin, metformin, morphine, pancuronium, procainamide, tenofovir, vancomycin: increased blood levels of both drugs

Drug-behaviors. Alcohol use: increased risk of drowsiness

Patient monitoring

• Monitor renal and hepatic function tests.

• Monitor patient for decreased GI motility and urinary retention.

See If patient has controlled angle-closure glaucoma, stay alert for severe eye pain accompanied by nausea, rainbows around lights, red eye, and blurred vision. Be prepared to treat immediately, as appropriate.

See Be aware that angioedema associated with life-threatening upper airway swelling may occur. If involvement of the tongue, hypopharynx, or larynx occurs, promptly discontinue drug and provide appropriate treatment.

Patient teaching

• Instruct patient to take tablet 1 hour before meals on an empty stomach or to take capsule in morning with water at least 1 hour before a meal.

• Instruct patient not to consume alcohol within 2 hours of taking extended-release capsule.

• Advise patient to consult prescriber before taking over-the-counter products such as antihistamines because these may increase risk of side effects.

• Inform patient that drug increases risk of heat prostration; describe symptoms and advise him to seek prompt medical attention if these occur.

• Caution patient to avoid driving and other hazardous activities until drug effects are known.

• Advise patient to avoid alcohol use.

• As appropriate, review all other significant adverse reactions and interactions, especially those related to the drugs and behaviors mentioned above.

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