Chemical and Microbiological Stability of Benazepril, Candesartan, Disulfiram, Fluconazole, Methocarbamol, and Pentoxifylline in SyrSpend® SF PH4.

This study evaluated the chemical and microbiological stability of six oral liquid formulations, benazepril hydrochloride, candesartan cilexetil, disulfiram, fluconazole, methocarbamol, and pentoxifylline, compounded in the suspending vehicle SyrSpend® SF PH4. Stability-indicating UHPLC methods were validated for each API and confirmed to be specific, precise, accurate, and linear within the analytical ranges tested. Forced degradation studies ensured method suitability for detecting potential decomposition pathways. Chemical stability was assessed over 90 days under room temperature and refrigerated storage, alongside pH monitoring and visual inspection. Antimicrobial effectiveness testing (USP <51>, Category 3: oral aqueous products) demonstrated that all formulations met preservative efficacy criteria at the final assigned BUD. Results revealed API-specific stability profiles: several formulations remained within 90-110% of label claim for up to 90 days, while others showed temperature degradation patterns dictating shorter BUDs. Overall, SyrSpend® SF PH4 proved to be a versatile and reliable vehicle for compounded oral liquids, supporting extended BUDs while maintaining physicochemical integrity and microbiological quality. These findings reveal dependent degradation patterns that dictate shorter BUDs. Overall, SyrSpend® SF PH4 proved to be a versatile and reliable vehicle for compounded oral liquids, supporting extended BUDs while preserving physicochemical integrity and microbiological quality. These findings provide evidence-based guidance for compounding pharmacists and reinforce the role of SyrSpend® SF PH4 in personalized pharmacotherapy.