fesoterodine fumarate: clinical use

Prescribing considerations

• Exclude urinary tract infection, obstructive disease and other causes of urinary frequency before treatment.
• Review renal and hepatic function and CYP3A4 or CYP2D6 interactions because these can alter active-metabolite exposure.
• Assess cumulative anticholinergic burden, particularly in older or cognitively vulnerable people.
• Use caution with bladder-outflow obstruction, reduced gastrointestinal motility, reflux, autonomic neuropathy, controlled narrow-angle glaucoma and relevant QT or cardiac risk.

Contraindications and cautions

• Urinary or gastric retention
• Uncontrolled narrow-angle glaucoma
• Myasthenia gravis
• Severe hepatic impairment
• Severe ulcerative colitis or toxic megacolon
• Potent CYP3A4 inhibition with moderate-to-severe renal or hepatic impairment
• Hypersensitivity to the active substance or formulation excipients; the selected Dr Reddy's product additionally lists peanut hypersensitivity

Monitoring

• Symptom response and continued clinical need
• Dry mouth, constipation, cognitive effects and other antimuscarinic adverse effects
• Difficulty voiding or evidence of urinary retention
• Renal and hepatic status where clinically relevant
• New interacting medicines and cumulative anticholinergic burden

Clinical pharmacology

Fesoterodine is a prodrug rapidly hydrolysed by plasma esterases to 5-hydroxymethyl tolterodine, a competitive muscarinic-receptor antagonist. CYP2D6 and CYP3A4 contribute to further metabolism, while renal excretion contributes substantially to elimination.

Formulation and product differences

• Both selected products are prolonged-release, lactose-containing tablets.
• The selected Dr Reddy's formulation also lists glycerol and a product-specific contraindication involving peanut hypersensitivity.
• The selected Aristo formulation does not list peanut hypersensitivity; check excipient suitability against the exact dispensed product.
• Storage conditions and packaging differ between products, so follow the pack instructions.

Modified-release tablet

Route: Oral

Strengths: 4 mg, 8 mg