Analysing the stability of two oral carbamazepine suspensions

To assess the physical, chemical and microbiological stability of two oral suspensions of carbamazepine at concentrations of 2.5% and 5%.

Both oral suspensions were compounded from powdered carbamazepine and Ora-Sweet SF(®) and Ora-Plus(®) commercial compounding excipients. At the 2, 4 and a 6-month marks, different quality assays were performed, comprising physical (pH, state of the suspension, organoleptic properties), chemical (HPLC) and microbiological assays.

The final concentration at 6 months for both the 2.5% and 5% carbamazapine suspensions was 22.9 and 45.9 mg/ml respectively, with calculated richness values between 90 and 110% fulfilling USP23 NF18 requirements. No changes in physical properties and no culture growth were observed during the study period.

Both oral suspensions are physically, chemically and microbiologically stable for at least 6 months when preserved at room temperature in amber glass flasks.