Stability Evaluation of Compounded Multidrug Oral Liquids in a Dual-Vehicle Suspending System

Extemporaneously compounded oral liquids are essential for patients unable to swallow solid dosage forms, although ensuring stability in aqueous systems remains challenging. This study evaluated the chemical, physical, and microbiological stability of formulations containing topiramate, omeprazole, gabapentin, ondansetron, and levofloxacin prepared in Flavor Sweet™ SF and Flavor Plus™, also known as Syra Sweet™ SF and Syra Plus™. Stability was assessed over 90 days at room temperature and under refrigeration using validated UHPLC methods, along with physical and microbiological analyses. Gabapentin, ondansetron, omeprazole, and topiramate remained stable for 90 days under both conditions, while levofloxacin was stable for 60 days at room temperature and 90 days refrigerated. All formulations showed consistent pH and acceptable microbiological quality, although precipitation in some samples led to discontinuation of analysis. These results support the suitability of the vehicle system and highlight the importance of formulation parameters in stability and beyond-use dating.