Toviaz 8 mg Should Not Be Split
Toviaz (fesoterodine) 8 mg tablets should not be split, crushed, or chewed, as this is an extended-release formulation that requires the intact tablet structure to maintain proper drug delivery and prevent potential overdose.
Why Splitting Is Contraindicated
Extended-Release Formulation Concerns
- Fesoterodine is formulated as an extended-release prodrug that is converted to its active metabolite (5-HMT) by nonspecific esterases after absorption 1
- Splitting extended-release tablets destroys the controlled-release mechanism, potentially causing uncontrolled release of the active component and risk of overdose 2
- The tablet must remain intact to ensure consistent, genotype-independent exposure to the active moiety throughout the 24-hour dosing period 1
Dosing Flexibility Without Splitting
- Fesoterodine is uniquely available in two distinct dosage strengths: 4 mg and 8 mg tablets 1
- The recommended approach is to start all patients on 4 mg once daily, then escalate to 8 mg if needed for optimal symptom control 3, 4
- Patients who cannot tolerate the 8 mg dose should be dose-reduced to the commercially available 4 mg tablet rather than attempting to split the 8 mg formulation 5
- In clinical trials, 71% of patients maintained the 8 mg dose long-term, while others successfully used dose reduction to 4 mg when needed 5
Clinical Evidence Supporting Two-Dose Strategy
- The 8 mg dose demonstrates statistically superior efficacy over 4 mg in reducing urgency urinary incontinence episodes, with diary-dry rates of 64% vs 57% respectively 3, 4
- Both doses were developed specifically to provide efficacious and well-tolerated regimens without requiring tablet manipulation 1
- The prodrug design allows for predictable pharmacokinetics at both dose levels, unlike tolterodine which has CYP2D6-dependent variability 1
Common Pitfall to Avoid
Do not attempt cost-saving measures by splitting higher-strength tablets, as this compromises the extended-release mechanism and patient safety. Instead, prescribe the appropriate commercially available strength (4 mg or 8 mg) based on individual efficacy and tolerability needs.