What is the recommended treatment and dosage of trospium for overactive bladder?

Trospium for Overactive Bladder: Treatment and Dosing

The recommended dosage of trospium chloride for overactive bladder is 60 mg once daily in the morning, taken with water on an empty stomach at least one hour before a meal. 1

Indications and Patient Selection

• Trospium chloride is indicated for treating overactive bladder (OAB) with symptoms of urge urinary incontinence, urgency, and urinary frequency 1
• Antimuscarinic medications like trospium should be offered as second-line therapy after behavioral therapies (bladder training, pelvic floor exercises, fluid management) have been attempted first 2
• Beta-3 agonists are typically preferred before antimuscarinic medications due to concerns about cognitive impairment and dementia risk with antimuscarinics 2

Dosing Regimens

Extended-Release Formulation (Preferred)

• 60 mg once daily in the morning 1
• Must be taken with water on an empty stomach, at least one hour before meals 1
• Food significantly reduces bioavailability (to 26% of fasting levels) 3

Immediate-Release Formulation

• 20 mg twice daily 4, 5, 6
• Efficacy is similar between once-daily extended-release and twice-daily immediate-release formulations, though once-daily dosing showed lower rates of dry mouth 4

Contraindications and Precautions

Absolute Contraindications: 1

• Urinary retention
• Gastric retention
• Uncontrolled narrow-angle glaucoma
• Known hypersensitivity to trospium (angioedema, rash, anaphylaxis have been reported)

Use with Extreme Caution in: 1

• Clinically significant bladder outflow obstruction (risk of urinary retention)
• Gastrointestinal obstructive disorders (risk of gastric retention)
• Controlled narrow-angle glaucoma (only if benefits outweigh risks with careful monitoring)
• Ulcerative colitis, intestinal atony, myasthenia gravis (decreased GI motility)

Renal Impairment Considerations

• Trospium is NOT recommended in patients with severe renal impairment (creatinine clearance <30 mL/min) 1
• Approximately 70% of trospium is excreted unchanged in urine, and elimination is significantly slowed in renal insufficiency 3
• Drug clearance correlates with serum creatinine concentration 3

Important Administration Guidelines

• Alcohol should not be consumed within 2 hours of trospium administration 1
• The extended-release capsule should be swallowed whole with water 1
• Consistent timing relative to meals is critical for maintaining therapeutic levels 3

Expected Efficacy and Onset

• Significant improvements in OAB symptoms occur by the end of week 1 and are sustained throughout treatment 4, 5, 6
• Trospium significantly reduces daily urinary frequency, urgency urinary incontinence episodes, urgency severity, and increases volume per void 4, 5, 6
• The once-daily 60 mg formulation showed the lowest reported rate of dry mouth in the oral antimuscarinic drug class 4

Common Adverse Effects

Most Common: 1, 4

• Dry mouth (8.7-10.7%)
• Constipation (8.5-9.4%)

Less Common:

• Central nervous system effects are rare due to trospium's quaternary ammonium structure, which minimizes blood-brain barrier penetration 3, 7
• Headache (1.0% vs 2.6% placebo) 4

Clinical Pearls

• Trospium has minimal drug-drug interactions because it is not metabolized by cytochrome P450 enzymes 3, 7
• The drug does not cross the blood-brain barrier, theoretically reducing cognitive side effects compared to tertiary amine antimuscarinics 3, 7
• Concomitant use with metformin reduces trospium exposure, though clinical significance is unclear 1
• Antacids may variably affect trospium absorption in individual patients 1

Treatment Failure Management

• If trospium is ineffective or poorly tolerated, consider switching to another antimuscarinic or a beta-3 agonist 8
• Combination therapy with behavioral interventions may provide additive benefits 2
• Third-line therapies include sacral neuromodulation, tibial nerve stimulation, or intradetrusor botulinum toxin injection 2, 8