Evaluation of stability of melatonin in extemporaneously compounded oral suspensions

Abstract Background Melatonin is commonly used to treat insomnia, sleep disturbance or hyperactivity disorders. It can be administered in paediatric patients as oral formulations prepared using either bulk powder or commercial products. Few studies have evaluated the stability of these oral formulations, but some storage conditions information may be lacking and a need has been identified for additional stability studies. Aim The aim of this research was to study the stability of extemporaneously prepared oral suspensions of melatonin (2 mg/mL), prepared from pure drug powder or commercial tablets using a proprietary dye‐free oral vehicle: Oral Mix SF (Medisca Pharmaceutique Inc.). Method Two melatonin oral liquid preparations were formulated: (a) tablets in Oral Mix SF and (b) pure drug powder in Oral Mix SF. Preparations were stored at room temperature (23–27°C) as well as under refrigeration (3–5°C) in amber plastic syringes (PreciseDose Dispenser™, Medisca Pharmaceutique Inc.) and amber polyethylene terephthalate (PET) bottles with appropriate closures for a period of 90 days. Preparations were assessed using a validated stability‐indicating high‐performance liquid chromatography method. Beyond use dates were evaluated by statistical analysis of the overall degradation trend. Results All preparations were physically and chemically stable for at least 90 days in all storage conditions at room temperature and under refrigeration. Conclusion Results showed that compared to other vehicles, these suspensions had equivalent stability, indicating that Oral Mix SF is a viable dye‐free and sugar‐free alternative for extemporaneous compounding of melatonin.