Liquid Medication Dosing Errors: Comparison of a Ready-to-Use Vigabatrin Solution to Reconstituted Solutions of Vigabatrin Powder for Oral Solution

Abstract

Introduction

Vigabatrin (VGB) is intended for use by caregivers of infants (1 month to 2 years old) diagnosed with infantile spasms (IS). Commercially available vigabatrin powders require caregiver reconstitution prior to oral administration. This study compared the ability of caregivers to accurately provide a targeted dose of vigabatrin using a ready-to-use (RTU) vigabatrin oral solution (VGB-RTU solution) and SABRIL^® (vigabatrin) powder for oral solution, Lundbeck LLC, (vigabatrin powder) without instruction from a healthcare professional.

Methods

A crossover comparative usability study with 30 lay users (15 caregivers with vigabatrin powder experience and 15 oral-syringe/medication preparation naïve users) which required users to deliver a single dose of both VGB-RTU surrogate solution and vigabatrin powder to a sample collection bottle was performed. Doses were measured analytically with a primary endpoint to deliver doses within ± 10% of the target dose of 1125 mg.

Results

All 30 participants administered VGB-RTU solution doses within ± 5% of the target, while only 23/30 of the vigabatrin powder doses were within ± 10%. All naïve users delivered vigabatrin doses using VGB-RTU solution within ± 5% of the target; whereas only 13/15 delivered doses within ± 10% for vigabatrin powder. All experienced vigabatrin users delivered calculated vigabatrin doses using VGB-RTU solution within ± 3%; whereas only 10/15 delivered doses within ± 10% for vigabatrin powder. Users were equally able to accurately deliver the prescribed volumes of both products. Calculated doses of VGB-RTU solution (mg) were significantly less variable (p < 0.0001) and more accurate (p < 0.01) than doses of vigabatrin powder.

Conclusion

Caregivers delivered more accurate and less variable doses of the ready-to-use solution compared to solutions prepared from vigabatrin powders for oral solution. These differences were shown to be due to caregiver errors in reconstituting vigabatrin powders for oral solution.