Generic Name

Fesoterodine Fumarate

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Classification

FDA Approved Indications

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

Mechanism of Action

Fesoterodine is a prodrug converted to 5-hydroxymethyl tolterodine, which is a muscarinic receptor antagonist. It inhibits acetylcholine on smooth muscle in the bladder, reducing involuntary detrusor muscle contractions.

Dosage and Administration

Adult: 4 mg once daily, may be increased to 8 mg if needed and tolerated

Pediatric: Not approved for pediatric use

Geriatric: Start at lower dose (4 mg) and titrate based on tolerability and response

Renal Impairment: Adjust dose based on renal function; typically cautious in severe impairment

Hepatic Impairment: Use with caution; no specific dose adjustment recommended but monitor closely

Pharmacokinetics

Absorption: Well absorbed, bioavailability ~52-54%

Distribution: Widely distributed; blood-to-plasma ratio ~7.5

Metabolism: Primarily via CYP3A4 and CYP2D6 to active metabolite

Excretion: Renal and fecal; parent drug minimally excreted unchanged

Half Life: Approximately 7-8 hours for the active metabolite

Contraindications

• Urinary retention
• Gastric retention
• Uncontrolled narrow-angle glaucoma
• Hypersensitivity to fesoterodine

Precautions

• Use with caution in patients with hepatic or renal impairment, urinary tract obstruction, or in the elderly due to increased risk of adverse effects

Adverse Reactions - Common

• Dry mouth (Frequent)
• Constipation (Frequent)
• Dizziness (Less common)

Adverse Reactions - Serious

• Urinary retention (Rare)
• Angioedema (Very rare)
• Allergic reactions including rash, pruritus (Rare)

Drug-Drug Interactions

• Other anticholinergic drugs
• CYP3A4 inhibitors (e.g., ketoconazole, clarithromycin)

Drug-Food Interactions

N/A

Drug-Herb Interactions

N/A

Nursing Implications

Patient/Family Teaching

• Take medication as prescribed, once daily
• Report any signs of urinary retention, severe dry mouth, or eye pain
• Avoid activities requiring alertness if experiencing dizziness
• Maintain hydration and fiber intake to reduce constipation

Special Considerations

Black Box Warnings:

• None for fesoterodine

Genetic Factors: Metabolism may vary based on CYP2D6 and CYP3A4 activity

Lab Test Interference: None documented

Overdose Management

Signs/Symptoms: Severe dry mouth, visual disturbances, urinary retention, tachycardia

Treatment: Supportive care, discontinue drug, symptomatic treatment, and monitor vital signs

Storage and Handling

Storage: Store at room temperature, away from moisture and light

Stability: Stable through expiration date when stored properly