Formulation and stability evaluation of an extemporaneously prepared baclofen suspension (1 mg/mL)

Abstract

Background: Baclofen is prescribed for both adults and children as a muscle relaxant, but no data exists to support an appropriate lower-dose extemporaneously compounded oral liquid suitable for young children in New Zealand. Aim: This study aimed to determine the stability of 1 mg/mL baclofen oral suspension over 30 days. Method: Baclofen suspensions were compounded (n = 6 per formulation) using suspending vehicles Ora-Blend® (OB) or Ora-Blend sugar-free® (OB SF) and stored at either 25°C/60% relative humidity or 2–8°C for 30 days. Organoleptic properties, sedimentation volume ratio, ease of redispersion, pH and baclofen content were determined. Results: Formulations required 2–3 inversions to redisperse at each time point. A colour change was observed from day 14 in the OB suspensions stored at both temperatures, likely due to the Maillard reaction, whereas no colour change was observed in any OB SF suspensions. The pH of all formulations remained between 4.5 and 4.6. Both OB and OB SF suspensions retained >90% of the initial baclofen concentration over 30 days. Conclusion: Although baclofen 1 mg/mL suspensions prepared in both OB and OB SF retained sufficient baclofen to be considered chemically stable in both storage conditions over the study period, OB SF is recommended as a preferred vehicle over OB formulations due to the colour change observed.