Abstracts

Rationale: Vigabatrin is intended for use by caregivers of infants (1 month to 2 years old) who have been diagnosed with Infantile Spasms. Commercially available vigabatrin powders must be reconstituted into a solution and administered orally.¹ Caregiver use error, difficulty in administering, and non-adherence are clinical challenges with this formulation.² The primary consideration with usability performance data is whether the patient receives a safe, effective, and accurate dose. The objective of this study was to compare the use of a ready-to-use vigabatrin oral solution (PRODUCT X) to an FDA-approved powder for oral solution (SABRIL).


Methods: A usability study was conducted with 30 lay users: 15 experienced SABRIL caregivers and 15 who were oral syringe naïve. All participants were asked to administer 1125 mg of vigabatrin to a sample collection bottle for both PRODUCT X and SABRIL. The dose delivered was measured analytically. Moderators recorded use errors, close calls, difficulties while preparing/administering each product, and time to administer.


Results: All 30 participants administered doses of PRODUCT X within 10% of the target dose of 1125 mg (range 1110-1154 mg), compared to 77% of SABRIL doses (range 425-1390 mg). The percentage difference between the average dose administered for PRODUCT X and the target dose was 0.89%, while for SABRIL, it was 10.95% (Figure 1).



Overall, while participants encountered similar counts of use errors during simulated use scenarios, use errors impacting patient dosing were much higher for SABRIL than PRODUCT X. (Table 1). Notably, use difficulty errors did not translate into actual adverse impacts to dosing.



For both PRODUCT X and SABRIL scenarios, use deviations impacting the amount of drug delivered were noted on the tasks of pulling the plunger to the correct syringe marking. Additional deviations noted during the SABRIL scenario included adding 10 mL of water per packet, identifying the second and third packets, and emptying the entire packet into the cup.



It took both experienced and naïve participants 1.5 times longer to administer vigabatrin doses for SABRIL than PRODUCT X. Overall, it took participants using PRODUCT X almost 4 minutes less (despite one-time activities such as seal removal and bottle adapter insertion) to administer a medication dose versus SABRIL.


Conclusions: All participants using PRODUCT X were administered an acceptable dose within 5% of the target. Only 77% of participants who used SABRIL administered a dose within 10% of the target. Overall, results suggest that using PRODUCT X provided significantly safer dosing versus SABRIL.



References 
1. Xu Z, et al. Efficacy of vigabatrin in the treatment of infantile epileptic spasms syndrome: A systematic review and meta-analysis. 2023;8:268-277.
2. Smith S, et al. Evaluation of product preparation and adherence trends in the Infantile Epileptic Spasms Syndrome (IESS) treated with vigabatrin powder solution: FAERS Database. AES, December 2023.


Funding: Funded by Pyros Pharmaceuticals.