Donald G. Grosset, Elaine G. Tyrrell , Katherine A. Grosset
Institute of Neurological Sciences, Southern General Hospital, G51 4TF Glasgow, United Kingdom. E-mail: donaldgrosset@gmail.com
DOI: 10.2340/16501977-1895

Objective: To explore the dose equivalence ratio and treatment costs for abobotulinumtoxinA and incobotulinumtoxinA
for patients with focal dystonias.
Design: Patient chart review.
Subjects/Patients: Adult patients with blepharospasm (n = 19), cervical dystonia (n = 122), hemifacial spasm (n = 91) or segmental/generalized dystonia (n = 19) at a neurology
outpatient clinic.
Methods: Patients were switched from established abobotulinumtoxinA therapy to incobotulinumtoxinA at a ~4:1 unit ratio. Dose requirements, injection intervals, treatment
efficacy, and adverse events were evaluated for a period of ≥ 1 year.
Results: Patients were switched from abobotulinumtoxinA to incobotulinumtoxinA with a mean dose ratio of 4. 07 (standard deviation (SD) 0. 50). After switching, incobotulinumtoxinA dose requirements remained stable; the mean (SD) dose ratio at the end of the review period (52–219 weeks
after switching) was 3. 89 (SD 0. 58). Injection intervals also
remained stable after switching. Adverse events were injection site pain (n = 45) and bruising (n = 4). Five patients (2. 0%) discontinued incobotulinumtoxinA treatment: 4 stopped
receiving injections, and 1 reverted to abobotulinumtoxinA. Switching to incobotulinumtoxinA reduced the mean toxin expenditure to 76. 7% of the cost of abobotulinumtoxinA.
Conclusion: For patients with conditions commonly treated in dystonia clinics, switching from abobotulinumtoxinA to incobotulinumtoxinA, given at equivalent doses (~4:1 unit ratio) at similar intervals, was effective, well tolerated and achieved cost savings.