Exceeding the maximum recommended dose of onabotulinumtoxinA in urologic patients

Although onabotulinumtoxinA (BTX) is commonly utilized by multiple specialists, it is unclear how often or reasons why patients receive more than the recommended maximum dose. The goal of this study was to determine if excess BTX use occurs in urologic practice.

This retrospective cohort identified patients who underwent intravesical BTX between 01/2013-12/2017 at an academic hospital. All BTX administrations for any indication were identified. Excess BTX was defined as receiving greater than the current recommended maximum dosage of 400 units within 3 months.

A total of 361 patient received intravesical BTX. These patients underwent 755 procedures using BTX, 673(89.1%) intravesical and 82(10.9%) non-urologic. Other site injections occurred in 14 patients, and 7 (50.0%) of these patients had at least one instance of excess. In these 7 patients, there were a total of 15 instances of excess use from either a single injection (3 instances) or a subsequent injection within 3 months (12 instances). No excess use occurred in patients who received only intravesical BTX. Discordance was noted between the administered dose, pharmacy dispensing information (46.9%), and nursing medication administration record (MAR) (54.3%). All dosages matched in only 39.2% procedures.

Although excess BTX use is overall infrequent in urologic practice, it is common in our patients prescribed the drug by non-urologic providers (50%). Pharmacy dispensing and nursing MAR information are unreliable in determining the actual administered dose. This highlights the need for providers to further discuss BTX use with patients and the need for improved tracking of BTX administration and communication across specialties.