The parameters API and preservative content, related substances, appearance and pH were studied under four different storage conditions. Samples were analyzed up to 12 months. Microbiological quality was studied in an 18-week in-use test based on a two-times daily dosing schedule.
The stability of the formulation was influenced by storage conditions and composition. A formulation containing amlodipine besylate, sucrose syrup and methyl paraben remained physically stable for 12 months at 4 °C with no loss of amlodipine content. Related substances increased during the study but remained below 0.5%. In-use stability was proven up to 18 weeks.
Storage under refrigerated conditions was necessary to prevent precipitation and to obtain an acceptable shelf-life. In conclusion, we have developed and validated an amlodipine oral solution, suitable for the pediatric population. This liquid formulation is preferred over manipulated commercial dosage forms or non-standardized extemporaneously compounded formulations.